Vulnerability-Lookup

CVE-2026-77755 (GCVE-0-2026-77755)

Vulnerability from cvelistv5 – Published: 2026-08-21 09:55 – Updated: 2026-08-21 12:09

Title

Denial of Service in MISP-STIX Import via Malformed or Oversized STIX Documents in misp-stix library

Summary

A denial-of-service vulnerability was identified in misp-stix when processing attacker-controlled STIX 1 or STIX 2 documents. The STIX import code used sys.exit() to handle several parsing and loading failures. Because SystemExit inherits from BaseException rather than Exception, these failures bypassed the exception handlers used by callers of the library. As a result, a malformed STIX document could terminate a long-running importer process instead of returning a recoverable parsing error. Additionally, no limit was imposed on the size of STIX documents before parsing. A submitted document was therefore read and materialised in memory before its validity or type was evaluated. Depending on the document and parsing path, processing could consume approximately two to seven times the input size in memory, allowing a sufficiently large STIX document to cause excessive memory and CPU consumption and potentially terminate or severely degrade the importing service. An attacker able to provide STIX content to a MISP-STIX import workflow could exploit either condition to affect availability. A malformed document could cause abnormal process termination through an uncaught SystemExit, while a large document could exhaust resources during deserialisation and conversion. The fixes replace process-terminating sys.exit() calls with catchable exceptions such as STIXLoadingError and MissingSTIXContentError, and extend exception handling around the complete STIX detection and conversion process. The importer also now enforces an input-size limit before parsing. The default maximum is 100 MB, can be adjusted by callers, and can explicitly be disabled when required. STIX 1 inputs are additionally checked for the expected root element before the complete XML tree is constructed. ImpactSuccessful exploitation can cause: * termination of a long-running MISP-STIX importer; * excessive memory allocation; * excessive CPU consumption; * degradation or temporary unavailability of services relying on the converter; * interruption of batch or automated STIX ingestion workflows.

Severity

8.7 (High)


                        
                          CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L

SSVC

Exploitation: none Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-08-21 12:06 UTC

CWE

CWE-400 - Uncontrolled Resource Consumption

Assigner

CIRCL ENISA root

References

2 references

URL	Tags
https://github.com/MISP/misp-stix/commit/e8e732ad	patch
https://github.com/MISP/misp-stix/commit/66119552	patch

Impacted products

1 product

Vendor	Product	Version	CPE status
misp	misp-stix	Affected: 0 , ≤ 2026.7.8 (semver)	guessed

Credits

🕵️‍♂️ Jeroen Pinoy 🐞 Christian Studer

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-77755",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-08-21T12:06:03.611904Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-08-21T12:09:16.956Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "misp-stix",
          "repo": "https://github.com/MISP/misp-stix/",
          "vendor": "misp",
          "versions": [
            {
              "lessThanOrEqual": "2026.7.8",
              "status": "affected",
              "version": "0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "Jeroen Pinoy"
        },
        {
          "lang": "en",
          "type": "remediation developer",
          "value": "Christian Studer"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "\u003cp\u003eA denial-of-service vulnerability was identified in \u003cstrong\u003emisp-stix\u003c/strong\u003e when processing attacker-controlled STIX 1 or STIX 2 documents.\u003c/p\u003e\u003cp\u003eThe STIX import code used \u003ccode\u003esys.exit()\u003c/code\u003e to handle several parsing and loading failures. Because \u003ccode\u003eSystemExit\u003c/code\u003e inherits from \u003ccode\u003eBaseException\u003c/code\u003e rather than \u003ccode\u003eException\u003c/code\u003e, these failures bypassed the exception handlers used by callers of the library. As a result, a malformed STIX document could terminate a long-running importer process instead of returning a recoverable parsing error.\u003c/p\u003e\u003cp\u003eAdditionally, no limit was imposed on the size of STIX documents before parsing. A submitted document was therefore read and materialised in memory before its validity or type was evaluated. Depending on the document and parsing path, processing could consume approximately \u003cstrong\u003etwo to seven times the input size in memory\u003c/strong\u003e, allowing a sufficiently large STIX document to cause excessive memory and CPU consumption and potentially terminate or severely degrade the importing service.\u003c/p\u003e\u003cp\u003eAn attacker able to provide STIX content to a MISP-STIX import workflow could exploit either condition to affect availability. A malformed document could cause abnormal process termination through an uncaught \u003ccode\u003eSystemExit\u003c/code\u003e, while a large document could exhaust resources during deserialisation and conversion.\u003c/p\u003e\u003cp\u003eThe fixes replace process-terminating \u003ccode\u003esys.exit()\u003c/code\u003e calls with catchable exceptions such as \u003ccode\u003eSTIXLoadingError\u003c/code\u003e and \u003ccode\u003eMissingSTIXContentError\u003c/code\u003e, and extend exception handling around the complete STIX detection and conversion process. The importer also now enforces an input-size limit before parsing. The default maximum is \u003cstrong\u003e100 MB\u003c/strong\u003e, can be adjusted by callers, and can explicitly be disabled when required. STIX 1 inputs are additionally checked for the expected root element before the complete XML tree is constructed.\u003c/p\u003e\u003ch2\u003eImpact\u003c/h2\u003e\u003cp\u003eSuccessful exploitation can cause:\u003c/p\u003e\u003cul\u003e\u003cli\u003etermination of a long-running MISP-STIX importer;\u003c/li\u003e\u003cli\u003eexcessive memory allocation;\u003c/li\u003e\u003cli\u003eexcessive CPU consumption;\u003c/li\u003e\u003cli\u003edegradation or temporary unavailability of services relying on the converter;\u003c/li\u003e\u003cli\u003einterruption of batch or automated STIX ingestion workflows.\u003c/li\u003e\u003c/ul\u003e\u003cbr\u003e"
            }
          ],
          "value": "A denial-of-service vulnerability was identified in misp-stix when processing attacker-controlled STIX 1 or STIX 2 documents.\n\nThe STIX import code used sys.exit() to handle several parsing and loading failures. Because SystemExit inherits from BaseException rather than Exception, these failures bypassed the exception handlers used by callers of the library. As a result, a malformed STIX document could terminate a long-running importer process instead of returning a recoverable parsing error.\n\nAdditionally, no limit was imposed on the size of STIX documents before parsing. A submitted document was therefore read and materialised in memory before its validity or type was evaluated. Depending on the document and parsing path, processing could consume approximately two to seven times the input size in memory, allowing a sufficiently large STIX document to cause excessive memory and CPU consumption and potentially terminate or severely degrade the importing service.\n\nAn attacker able to provide STIX content to a MISP-STIX import workflow could exploit either condition to affect availability. A malformed document could cause abnormal process termination through an uncaught SystemExit, while a large document could exhaust resources during deserialisation and conversion.\n\nThe fixes replace process-terminating sys.exit() calls with catchable exceptions such as STIXLoadingError and MissingSTIXContentError, and extend exception handling around the complete STIX detection and conversion process. The importer also now enforces an input-size limit before parsing. The default maximum is 100 MB, can be adjusted by callers, and can explicitly be disabled when required. STIX 1 inputs are additionally checked for the expected root element before the complete XML tree is constructed.\n\nImpactSuccessful exploitation can cause:\n\n  *  termination of a long-running MISP-STIX importer;\n  *  excessive memory allocation;\n  *  excessive CPU consumption;\n  *  degradation or temporary unavailability of services relying on the converter;\n  *  interruption of batch or automated STIX ingestion workflows."
        }
      ],
      "impacts": [
        {
          "capecId": "CAPEC-130",
          "descriptions": [
            {
              "lang": "en",
              "value": "CAPEC-130 Excessive Allocation"
            }
          ]
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "LOW",
            "attackRequirements": "NONE",
            "attackVector": "NETWORK",
            "baseScore": 8.7,
            "baseSeverity": "HIGH",
            "privilegesRequired": "NONE",
            "providerUrgency": "NOT_DEFINED",
            "subAvailabilityImpact": "LOW",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "valueDensity": "NOT_DEFINED",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L",
            "version": "4.0",
            "vulnAvailabilityImpact": "HIGH",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "NONE",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-400",
              "description": "CWE-400 Uncontrolled Resource Consumption",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-21T09:55:11.079Z",
        "orgId": "5a6e4751-2f3f-4070-9419-94fb35b644e8",
        "shortName": "CIRCL"
      },
      "references": [
        {
          "tags": [
            "patch"
          ],
          "url": "https://github.com/MISP/misp-stix/commit/e8e732ad"
        },
        {
          "tags": [
            "patch"
          ],
          "url": "https://github.com/MISP/misp-stix/commit/66119552"
        }
      ],
      "source": {
        "discovery": "UNKNOWN"
      },
      "title": "Denial of Service in MISP-STIX Import via Malformed or Oversized STIX Documents in misp-stix library",
      "x_generator": {
        "engine": "Vulnogram 0.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "5a6e4751-2f3f-4070-9419-94fb35b644e8",
    "assignerShortName": "CIRCL",
    "cveId": "CVE-2026-77755",
    "datePublished": "2026-08-21T09:55:11.079Z",
    "dateReserved": "2026-08-21T09:55:04.399Z",
    "dateUpdated": "2026-08-21T12:09:16.956Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-77755",
      "date": "2026-08-23",
      "epss": "0.00304",
      "percentile": "0.23205"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-77755\",\"sourceIdentifier\":\"5a6e4751-2f3f-4070-9419-94fb35b644e8\",\"published\":\"2026-08-21T10:16:39.363\",\"lastModified\":\"2026-08-21T12:16:36.393\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"A denial-of-service vulnerability was identified in misp-stix when processing attacker-controlled STIX 1 or STIX 2 documents.\\n\\nThe STIX import code used sys.exit() to handle several parsing and loading failures. Because SystemExit inherits from BaseException rather than Exception, these failures bypassed the exception handlers used by callers of the library. As a result, a malformed STIX document could terminate a long-running importer process instead of returning a recoverable parsing error.\\n\\nAdditionally, no limit was imposed on the size of STIX documents before parsing. A submitted document was therefore read and materialised in memory before its validity or type was evaluated. Depending on the document and parsing path, processing could consume approximately two to seven times the input size in memory, allowing a sufficiently large STIX document to cause excessive memory and CPU consumption and potentially terminate or severely degrade the importing service.\\n\\nAn attacker able to provide STIX content to a MISP-STIX import workflow could exploit either condition to affect availability. A malformed document could cause abnormal process termination through an uncaught SystemExit, while a large document could exhaust resources during deserialisation and conversion.\\n\\nThe fixes replace process-terminating sys.exit() calls with catchable exceptions such as STIXLoadingError and MissingSTIXContentError, and extend exception handling around the complete STIX detection and conversion process. The importer also now enforces an input-size limit before parsing. The default maximum is 100 MB, can be adjusted by callers, and can explicitly be disabled when required. STIX 1 inputs are additionally checked for the expected root element before the complete XML tree is constructed.\\n\\nImpactSuccessful exploitation can cause:\\n\\n  *  termination of a long-running MISP-STIX importer;\\n  *  excessive memory allocation;\\n  *  excessive CPU consumption;\\n  *  degradation or temporary unavailability of services relying on the converter;\\n  *  interruption of batch or automated STIX ingestion workflows.\"}],\"affected\":[{\"source\":\"5a6e4751-2f3f-4070-9419-94fb35b644e8\",\"affectedData\":[{\"vendor\":\"misp\",\"product\":\"misp-stix\",\"defaultStatus\":\"unaffected\",\"repo\":\"https://github.com/MISP/misp-stix/\",\"versions\":[{\"version\":\"0\",\"lessThanOrEqual\":\"2026.7.8\",\"versionType\":\"semver\",\"status\":\"affected\"}]}]}],\"metrics\":{\"cvssMetricV40\":[{\"source\":\"5a6e4751-2f3f-4070-9419-94fb35b644e8\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"4.0\",\"vectorString\":\"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X\",\"baseScore\":8.7,\"baseSeverity\":\"HIGH\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"attackRequirements\":\"NONE\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"vulnConfidentialityImpact\":\"NONE\",\"vulnIntegrityImpact\":\"NONE\",\"vulnAvailabilityImpact\":\"HIGH\",\"subConfidentialityImpact\":\"NONE\",\"subIntegrityImpact\":\"NONE\",\"subAvailabilityImpact\":\"LOW\",\"exploitMaturity\":\"NOT_DEFINED\",\"confidentialityRequirement\":\"NOT_DEFINED\",\"integrityRequirement\":\"NOT_DEFINED\",\"availabilityRequirement\":\"NOT_DEFINED\",\"modifiedAttackVector\":\"NOT_DEFINED\",\"modifiedAttackComplexity\":\"NOT_DEFINED\",\"modifiedAttackRequirements\":\"NOT_DEFINED\",\"modifiedPrivilegesRequired\":\"NOT_DEFINED\",\"modifiedUserInteraction\":\"NOT_DEFINED\",\"modifiedVulnConfidentialityImpact\":\"NOT_DEFINED\",\"modifiedVulnIntegrityImpact\":\"NOT_DEFINED\",\"modifiedVulnAvailabilityImpact\":\"NOT_DEFINED\",\"modifiedSubConfidentialityImpact\":\"NOT_DEFINED\",\"modifiedSubIntegrityImpact\":\"NOT_DEFINED\",\"modifiedSubAvailabilityImpact\":\"NOT_DEFINED\",\"Safety\":\"NOT_DEFINED\",\"Automatable\":\"NOT_DEFINED\",\"Recovery\":\"NOT_DEFINED\",\"valueDensity\":\"NOT_DEFINED\",\"vulnerabilityResponseEffort\":\"NOT_DEFINED\",\"providerUrgency\":\"NOT_DEFINED\"}}],\"ssvcV203\":[{\"source\":\"134c704f-9b21-4f2e-91b3-4a467353bcc0\",\"ssvcData\":{\"timestamp\":\"2026-08-21T12:06:03.611904Z\",\"id\":\"CVE-2026-77755\",\"options\":[{\"exploitation\":\"none\"},{\"automatable\":\"yes\"},{\"technicalImpact\":\"partial\"}],\"role\":\"CISA Coordinator\",\"version\":\"2.0.3\"}}]},\"weaknesses\":[{\"source\":\"5a6e4751-2f3f-4070-9419-94fb35b644e8\",\"type\":\"Secondary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-400\"}]}],\"references\":[{\"url\":\"https://github.com/MISP/misp-stix/commit/66119552\",\"source\":\"5a6e4751-2f3f-4070-9419-94fb35b644e8\"},{\"url\":\"https://github.com/MISP/misp-stix/commit/e8e732ad\",\"source\":\"5a6e4751-2f3f-4070-9419-94fb35b644e8\"}]}}",
    "vulnrichment": {
      "containers": "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-77755\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"yes\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-08-21T12:06:03.611904Z\"}}}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-08-21T12:09:06.748Z\"}}], \"cna\": {\"title\": \"Denial of Service in MISP-STIX Import via Malformed or Oversized STIX Documents in misp-stix library\", \"source\": {\"discovery\": \"UNKNOWN\"}, \"credits\": [{\"lang\": \"en\", \"type\": \"finder\", \"value\": \"Jeroen Pinoy\"}, {\"lang\": \"en\", \"type\": \"remediation developer\", \"value\": \"Christian Studer\"}], \"impacts\": [{\"capecId\": \"CAPEC-130\", \"descriptions\": [{\"lang\": \"en\", \"value\": \"CAPEC-130 Excessive Allocation\"}]}], \"metrics\": [{\"format\": \"CVSS\", \"cvssV4_0\": {\"Safety\": \"NOT_DEFINED\", \"version\": \"4.0\", \"Recovery\": \"NOT_DEFINED\", \"baseScore\": 8.7, \"Automatable\": \"NOT_DEFINED\", \"attackVector\": \"NETWORK\", \"baseSeverity\": \"HIGH\", \"valueDensity\": \"NOT_DEFINED\", \"vectorString\": \"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L\", \"providerUrgency\": \"NOT_DEFINED\", \"userInteraction\": \"NONE\", \"attackComplexity\": \"LOW\", \"attackRequirements\": \"NONE\", \"privilegesRequired\": \"NONE\", \"subIntegrityImpact\": \"NONE\", \"vulnIntegrityImpact\": \"NONE\", \"subAvailabilityImpact\": \"LOW\", \"vulnAvailabilityImpact\": \"HIGH\", \"subConfidentialityImpact\": \"NONE\", \"vulnConfidentialityImpact\": \"NONE\", \"vulnerabilityResponseEffort\": \"NOT_DEFINED\"}, \"scenarios\": [{\"lang\": \"en\", \"value\": \"GENERAL\"}]}], \"affected\": [{\"repo\": \"https://github.com/MISP/misp-stix/\", \"vendor\": \"misp\", \"product\": \"misp-stix\", \"versions\": [{\"status\": \"affected\", \"version\": \"0\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"2026.7.8\"}], \"defaultStatus\": \"unaffected\"}], \"references\": [{\"url\": \"https://github.com/MISP/misp-stix/commit/e8e732ad\", \"tags\": [\"patch\"]}, {\"url\": \"https://github.com/MISP/misp-stix/commit/66119552\", \"tags\": [\"patch\"]}], \"x_generator\": {\"engine\": \"Vulnogram 0.2.0\"}, \"descriptions\": [{\"lang\": \"en\", \"value\": \"A denial-of-service vulnerability was identified in misp-stix when processing attacker-controlled STIX 1 or STIX 2 documents.\\n\\nThe STIX import code used sys.exit() to handle several parsing and loading failures. Because SystemExit inherits from BaseException rather than Exception, these failures bypassed the exception handlers used by callers of the library. As a result, a malformed STIX document could terminate a long-running importer process instead of returning a recoverable parsing error.\\n\\nAdditionally, no limit was imposed on the size of STIX documents before parsing. A submitted document was therefore read and materialised in memory before its validity or type was evaluated. Depending on the document and parsing path, processing could consume approximately two to seven times the input size in memory, allowing a sufficiently large STIX document to cause excessive memory and CPU consumption and potentially terminate or severely degrade the importing service.\\n\\nAn attacker able to provide STIX content to a MISP-STIX import workflow could exploit either condition to affect availability. A malformed document could cause abnormal process termination through an uncaught SystemExit, while a large document could exhaust resources during deserialisation and conversion.\\n\\nThe fixes replace process-terminating sys.exit() calls with catchable exceptions such as STIXLoadingError and MissingSTIXContentError, and extend exception handling around the complete STIX detection and conversion process. The importer also now enforces an input-size limit before parsing. The default maximum is 100 MB, can be adjusted by callers, and can explicitly be disabled when required. STIX 1 inputs are additionally checked for the expected root element before the complete XML tree is constructed.\\n\\nImpactSuccessful exploitation can cause:\\n\\n  *  termination of a long-running MISP-STIX importer;\\n  *  excessive memory allocation;\\n  *  excessive CPU consumption;\\n  *  degradation or temporary unavailability of services relying on the converter;\\n  *  interruption of batch or automated STIX ingestion workflows.\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"\u003cp\u003eA denial-of-service vulnerability was identified in \u003cstrong\u003emisp-stix\u003c/strong\u003e when processing attacker-controlled STIX 1 or STIX 2 documents.\u003c/p\u003e\u003cp\u003eThe STIX import code used \u003ccode\u003esys.exit()\u003c/code\u003e to handle several parsing and loading failures. Because \u003ccode\u003eSystemExit\u003c/code\u003e inherits from \u003ccode\u003eBaseException\u003c/code\u003e rather than \u003ccode\u003eException\u003c/code\u003e, these failures bypassed the exception handlers used by callers of the library. As a result, a malformed STIX document could terminate a long-running importer process instead of returning a recoverable parsing error.\u003c/p\u003e\u003cp\u003eAdditionally, no limit was imposed on the size of STIX documents before parsing. A submitted document was therefore read and materialised in memory before its validity or type was evaluated. Depending on the document and parsing path, processing could consume approximately \u003cstrong\u003etwo to seven times the input size in memory\u003c/strong\u003e, allowing a sufficiently large STIX document to cause excessive memory and CPU consumption and potentially terminate or severely degrade the importing service.\u003c/p\u003e\u003cp\u003eAn attacker able to provide STIX content to a MISP-STIX import workflow could exploit either condition to affect availability. A malformed document could cause abnormal process termination through an uncaught \u003ccode\u003eSystemExit\u003c/code\u003e, while a large document could exhaust resources during deserialisation and conversion.\u003c/p\u003e\u003cp\u003eThe fixes replace process-terminating \u003ccode\u003esys.exit()\u003c/code\u003e calls with catchable exceptions such as \u003ccode\u003eSTIXLoadingError\u003c/code\u003e and \u003ccode\u003eMissingSTIXContentError\u003c/code\u003e, and extend exception handling around the complete STIX detection and conversion process. The importer also now enforces an input-size limit before parsing. The default maximum is \u003cstrong\u003e100 MB\u003c/strong\u003e, can be adjusted by callers, and can explicitly be disabled when required. STIX 1 inputs are additionally checked for the expected root element before the complete XML tree is constructed.\u003c/p\u003e\u003ch2\u003eImpact\u003c/h2\u003e\u003cp\u003eSuccessful exploitation can cause:\u003c/p\u003e\u003cul\u003e\u003cli\u003etermination of a long-running MISP-STIX importer;\u003c/li\u003e\u003cli\u003eexcessive memory allocation;\u003c/li\u003e\u003cli\u003eexcessive CPU consumption;\u003c/li\u003e\u003cli\u003edegradation or temporary unavailability of services relying on the converter;\u003c/li\u003e\u003cli\u003einterruption of batch or automated STIX ingestion workflows.\u003c/li\u003e\u003c/ul\u003e\u003cbr\u003e\", \"base64\": false}]}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-400\", \"description\": \"CWE-400 Uncontrolled Resource Consumption\"}]}], \"providerMetadata\": {\"orgId\": \"5a6e4751-2f3f-4070-9419-94fb35b644e8\", \"shortName\": \"CIRCL\", \"dateUpdated\": \"2026-08-21T09:55:11.079Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-77755\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-08-21T12:09:16.956Z\", \"dateReserved\": \"2026-08-21T09:55:04.399Z\", \"assignerOrgId\": \"5a6e4751-2f3f-4070-9419-94fb35b644e8\", \"datePublished\": \"2026-08-21T09:55:11.079Z\", \"assignerShortName\": \"CIRCL\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}

FKIE_CVE-2026-77755

Vulnerability from fkie_nvd - Published: 2026-08-21 10:16 - Updated: 2026-08-21 12:16

Severity

8.7 (High) - CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L

Summary

References

	URL	Tags
	5a6e4751-2f3f-4070-9419-94fb35b644e8	https://github.com/MISP/misp-stix/commit/66119552
	5a6e4751-2f3f-4070-9419-94fb35b644e8	https://github.com/MISP/misp-stix/commit/e8e732ad

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "misp-stix",
          "repo": "https://github.com/MISP/misp-stix/",
          "vendor": "misp",
          "versions": [
            {
              "lessThanOrEqual": "2026.7.8",
              "status": "affected",
              "version": "0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "source": "5a6e4751-2f3f-4070-9419-94fb35b644e8"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "A denial-of-service vulnerability was identified in misp-stix when processing attacker-controlled STIX 1 or STIX 2 documents.\n\nThe STIX import code used sys.exit() to handle several parsing and loading failures. Because SystemExit inherits from BaseException rather than Exception, these failures bypassed the exception handlers used by callers of the library. As a result, a malformed STIX document could terminate a long-running importer process instead of returning a recoverable parsing error.\n\nAdditionally, no limit was imposed on the size of STIX documents before parsing. A submitted document was therefore read and materialised in memory before its validity or type was evaluated. Depending on the document and parsing path, processing could consume approximately two to seven times the input size in memory, allowing a sufficiently large STIX document to cause excessive memory and CPU consumption and potentially terminate or severely degrade the importing service.\n\nAn attacker able to provide STIX content to a MISP-STIX import workflow could exploit either condition to affect availability. A malformed document could cause abnormal process termination through an uncaught SystemExit, while a large document could exhaust resources during deserialisation and conversion.\n\nThe fixes replace process-terminating sys.exit() calls with catchable exceptions such as STIXLoadingError and MissingSTIXContentError, and extend exception handling around the complete STIX detection and conversion process. The importer also now enforces an input-size limit before parsing. The default maximum is 100 MB, can be adjusted by callers, and can explicitly be disabled when required. STIX 1 inputs are additionally checked for the expected root element before the complete XML tree is constructed.\n\nImpactSuccessful exploitation can cause:\n\n  *  termination of a long-running MISP-STIX importer;\n  *  excessive memory allocation;\n  *  excessive CPU consumption;\n  *  degradation or temporary unavailability of services relying on the converter;\n  *  interruption of batch or automated STIX ingestion workflows."
    }
  ],
  "id": "CVE-2026-77755",
  "lastModified": "2026-08-21T12:16:36.393",
  "metrics": {
    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "LOW",
          "attackRequirements": "NONE",
          "attackVector": "NETWORK",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 8.7,
          "baseSeverity": "HIGH",
          "confidentialityRequirement": "NOT_DEFINED",
          "exploitMaturity": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "privilegesRequired": "NONE",
          "providerUrgency": "NOT_DEFINED",
          "subAvailabilityImpact": "LOW",
          "subConfidentialityImpact": "NONE",
          "subIntegrityImpact": "NONE",
          "userInteraction": "NONE",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
          "version": "4.0",
          "vulnAvailabilityImpact": "HIGH",
          "vulnConfidentialityImpact": "NONE",
          "vulnIntegrityImpact": "NONE",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "5a6e4751-2f3f-4070-9419-94fb35b644e8",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-77755",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-08-21T12:06:03.611904Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-08-21T10:16:39.363",
  "references": [
    {
      "source": "5a6e4751-2f3f-4070-9419-94fb35b644e8",
      "url": "https://github.com/MISP/misp-stix/commit/66119552"
    },
    {
      "source": "5a6e4751-2f3f-4070-9419-94fb35b644e8",
      "url": "https://github.com/MISP/misp-stix/commit/e8e732ad"
    }
  ],
  "sourceIdentifier": "5a6e4751-2f3f-4070-9419-94fb35b644e8",
  "vulnStatus": "Received",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-400"
        }
      ],
      "source": "5a6e4751-2f3f-4070-9419-94fb35b644e8",
      "type": "Secondary"
    }
  ]
}

GCVE-1-2026-20053 (CVE-2026-77755)

Vulnerability from gna-1 – Published: 2026-08-21 09:54 – Updated: 2026-08-21 09:55

Title

Denial of Service in MISP-STIX Import via Malformed or Oversized STIX Documents in misp-stix library

Summary

Severity

8.7 (High)


                        
                          CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L

CWE

CWE-400 - Uncontrolled Resource Consumption

Assigner

GNA-1

References

2 references

URL	Tags
https://github.com/MISP/misp-stix/commit/e8e732ad	patch
https://github.com/MISP/misp-stix/commit/66119552	patch

Impacted products

1 product

Vendor	Product	Version
misp	misp-stix	Affected: 0 , ≤ 2026.7.8 (semver)

Credits

🕵️‍♂️ Jeroen Pinoy 🐞 Christian Studer

JSON

To clipboard

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "misp-stix",
          "repo": "https://github.com/MISP/misp-stix/",
          "vendor": "misp",
          "versions": [
            {
              "lessThanOrEqual": "2026.7.8",
              "status": "affected",
              "version": "0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "Jeroen Pinoy"
        },
        {
          "lang": "en",
          "type": "remediation developer",
          "value": "Christian Studer"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "\u003cp\u003eA denial-of-service vulnerability was identified in \u003cstrong\u003emisp-stix\u003c/strong\u003e when processing attacker-controlled STIX 1 or STIX 2 documents.\u003c/p\u003e\u003cp\u003eThe STIX import code used \u003ccode\u003esys.exit()\u003c/code\u003e to handle several parsing and loading failures. Because \u003ccode\u003eSystemExit\u003c/code\u003e inherits from \u003ccode\u003eBaseException\u003c/code\u003e rather than \u003ccode\u003eException\u003c/code\u003e, these failures bypassed the exception handlers used by callers of the library. As a result, a malformed STIX document could terminate a long-running importer process instead of returning a recoverable parsing error.\u003c/p\u003e\u003cp\u003eAdditionally, no limit was imposed on the size of STIX documents before parsing. A submitted document was therefore read and materialised in memory before its validity or type was evaluated. Depending on the document and parsing path, processing could consume approximately \u003cstrong\u003etwo to seven times the input size in memory\u003c/strong\u003e, allowing a sufficiently large STIX document to cause excessive memory and CPU consumption and potentially terminate or severely degrade the importing service.\u003c/p\u003e\u003cp\u003eAn attacker able to provide STIX content to a MISP-STIX import workflow could exploit either condition to affect availability. A malformed document could cause abnormal process termination through an uncaught \u003ccode\u003eSystemExit\u003c/code\u003e, while a large document could exhaust resources during deserialisation and conversion.\u003c/p\u003e\u003cp\u003eThe fixes replace process-terminating \u003ccode\u003esys.exit()\u003c/code\u003e calls with catchable exceptions such as \u003ccode\u003eSTIXLoadingError\u003c/code\u003e and \u003ccode\u003eMissingSTIXContentError\u003c/code\u003e, and extend exception handling around the complete STIX detection and conversion process. The importer also now enforces an input-size limit before parsing. The default maximum is \u003cstrong\u003e100 MB\u003c/strong\u003e, can be adjusted by callers, and can explicitly be disabled when required. STIX 1 inputs are additionally checked for the expected root element before the complete XML tree is constructed.\u003c/p\u003e\u003ch2\u003eImpact\u003c/h2\u003e\u003cp\u003eSuccessful exploitation can cause:\u003c/p\u003e\u003cul\u003e\u003cli\u003etermination of a long-running MISP-STIX importer;\u003c/li\u003e\u003cli\u003eexcessive memory allocation;\u003c/li\u003e\u003cli\u003eexcessive CPU consumption;\u003c/li\u003e\u003cli\u003edegradation or temporary unavailability of services relying on the converter;\u003c/li\u003e\u003cli\u003einterruption of batch or automated STIX ingestion workflows.\u003c/li\u003e\u003c/ul\u003e\u003cbr\u003e"
            }
          ],
          "value": "A denial-of-service vulnerability was identified in misp-stix when processing attacker-controlled STIX 1 or STIX 2 documents.\n\nThe STIX import code used sys.exit() to handle several parsing and loading failures. Because SystemExit inherits from BaseException rather than Exception, these failures bypassed the exception handlers used by callers of the library. As a result, a malformed STIX document could terminate a long-running importer process instead of returning a recoverable parsing error.\n\nAdditionally, no limit was imposed on the size of STIX documents before parsing. A submitted document was therefore read and materialised in memory before its validity or type was evaluated. Depending on the document and parsing path, processing could consume approximately two to seven times the input size in memory, allowing a sufficiently large STIX document to cause excessive memory and CPU consumption and potentially terminate or severely degrade the importing service.\n\nAn attacker able to provide STIX content to a MISP-STIX import workflow could exploit either condition to affect availability. A malformed document could cause abnormal process termination through an uncaught SystemExit, while a large document could exhaust resources during deserialisation and conversion.\n\nThe fixes replace process-terminating sys.exit() calls with catchable exceptions such as STIXLoadingError and MissingSTIXContentError, and extend exception handling around the complete STIX detection and conversion process. The importer also now enforces an input-size limit before parsing. The default maximum is 100 MB, can be adjusted by callers, and can explicitly be disabled when required. STIX 1 inputs are additionally checked for the expected root element before the complete XML tree is constructed.\n\nImpactSuccessful exploitation can cause:\n\n  *  termination of a long-running MISP-STIX importer;\n  *  excessive memory allocation;\n  *  excessive CPU consumption;\n  *  degradation or temporary unavailability of services relying on the converter;\n  *  interruption of batch or automated STIX ingestion workflows."
        }
      ],
      "impacts": [
        {
          "capecId": "CAPEC-130",
          "descriptions": [
            {
              "lang": "en",
              "value": "CAPEC-130 Excessive Allocation"
            }
          ]
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "LOW",
            "attackRequirements": "NONE",
            "attackVector": "NETWORK",
            "baseScore": 8.7,
            "baseSeverity": "HIGH",
            "privilegesRequired": "NONE",
            "providerUrgency": "NOT_DEFINED",
            "subAvailabilityImpact": "LOW",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "valueDensity": "NOT_DEFINED",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L",
            "version": "4.0",
            "vulnAvailabilityImpact": "HIGH",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "NONE",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-400",
              "description": "CWE-400 Uncontrolled Resource Consumption",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "orgId": "00000000-0000-4000-9000-000000000000"
      },
      "references": [
        {
          "tags": [
            "patch"
          ],
          "url": "https://github.com/MISP/misp-stix/commit/e8e732ad"
        },
        {
          "tags": [
            "patch"
          ],
          "url": "https://github.com/MISP/misp-stix/commit/66119552"
        }
      ],
      "source": {
        "discovery": "UNKNOWN"
      },
      "title": "Denial of Service in MISP-STIX Import via Malformed or Oversized STIX Documents in misp-stix library",
      "x_generator": {
        "engine": "Vulnogram 0.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "00000000-0000-4000-9000-000000000000",
    "cveId": "CVE-2026-77755",
    "datePublished": "2026-08-21T09:54:53.412150Z",
    "dateReserved": "2026-08-21T09:55:04.399Z",
    "dateUpdated": "2026-08-21T09:55:05.204624Z",
    "requesterUserId": "00000000-0000-4000-9000-000000000000",
    "serial": 1,
    "state": "PUBLISHED",
    "vulnId": "gcve-1-2026-20053"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.1"
}

GHSA-65GX-WJVJ-88J8

Vulnerability from github – Published: 2026-08-21 12:30 – Updated: 2026-08-21 12:30

Details

A denial-of-service vulnerability was identified in misp-stix when processing attacker-controlled STIX 1 or STIX 2 documents.

The STIX import code used sys.exit() to handle several parsing and loading failures. Because SystemExit inherits from BaseException rather than Exception, these failures bypassed the exception handlers used by callers of the library. As a result, a malformed STIX document could terminate a long-running importer process instead of returning a recoverable parsing error.

Additionally, no limit was imposed on the size of STIX documents before parsing. A submitted document was therefore read and materialised in memory before its validity or type was evaluated. Depending on the document and parsing path, processing could consume approximately two to seven times the input size in memory, allowing a sufficiently large STIX document to cause excessive memory and CPU consumption and potentially terminate or severely degrade the importing service.

An attacker able to provide STIX content to a MISP-STIX import workflow could exploit either condition to affect availability. A malformed document could cause abnormal process termination through an uncaught SystemExit, while a large document could exhaust resources during deserialisation and conversion.

The fixes replace process-terminating sys.exit() calls with catchable exceptions such as STIXLoadingError and MissingSTIXContentError, and extend exception handling around the complete STIX detection and conversion process. The importer also now enforces an input-size limit before parsing. The default maximum is 100 MB, can be adjusted by callers, and can explicitly be disabled when required. STIX 1 inputs are additionally checked for the expected root element before the complete XML tree is constructed.

ImpactSuccessful exploitation can cause:

termination of a long-running MISP-STIX importer;
excessive memory allocation;
excessive CPU consumption;
degradation or temporary unavailability of services relying on the converter;
interruption of batch or automated STIX ingestion workflows.

Severity

8.7 (High)


                  
                    CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L

Show details on source website

JSON

To clipboard

{
  "affected": [],
  "aliases": [
    "CVE-2026-77755"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-400"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-21T10:16:39Z",
    "severity": "HIGH"
  },
  "details": "A denial-of-service vulnerability was identified in misp-stix when processing attacker-controlled STIX 1 or STIX 2 documents.\n\nThe STIX import code used sys.exit() to handle several parsing and loading failures. Because SystemExit inherits from BaseException rather than Exception, these failures bypassed the exception handlers used by callers of the library. As a result, a malformed STIX document could terminate a long-running importer process instead of returning a recoverable parsing error.\n\nAdditionally, no limit was imposed on the size of STIX documents before parsing. A submitted document was therefore read and materialised in memory before its validity or type was evaluated. Depending on the document and parsing path, processing could consume approximately two to seven times the input size in memory, allowing a sufficiently large STIX document to cause excessive memory and CPU consumption and potentially terminate or severely degrade the importing service.\n\nAn attacker able to provide STIX content to a MISP-STIX import workflow could exploit either condition to affect availability. A malformed document could cause abnormal process termination through an uncaught SystemExit, while a large document could exhaust resources during deserialisation and conversion.\n\nThe fixes replace process-terminating sys.exit() calls with catchable exceptions such as STIXLoadingError and MissingSTIXContentError, and extend exception handling around the complete STIX detection and conversion process. The importer also now enforces an input-size limit before parsing. The default maximum is 100 MB, can be adjusted by callers, and can explicitly be disabled when required. STIX 1 inputs are additionally checked for the expected root element before the complete XML tree is constructed.\n\nImpactSuccessful exploitation can cause:\n\n  *  termination of a long-running MISP-STIX importer;\n  *  excessive memory allocation;\n  *  excessive CPU consumption;\n  *  degradation or temporary unavailability of services relying on the converter;\n  *  interruption of batch or automated STIX ingestion workflows.",
  "id": "GHSA-65gx-wjvj-88j8",
  "modified": "2026-08-21T12:30:31Z",
  "published": "2026-08-21T12:30:31Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-77755"
    },
    {
      "type": "WEB",
      "url": "https://github.com/MISP/misp-stix/commit/66119552"
    },
    {
      "type": "WEB",
      "url": "https://github.com/MISP/misp-stix/commit/e8e732ad"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
      "type": "CVSS_V4"
    }
  ]
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.

Action not permitted

CVE-2026-77755 (GCVE-0-2026-77755)

FKIE_CVE-2026-77755

GCVE-1-2026-20053 (CVE-2026-77755)

GHSA-65GX-WJVJ-88J8

Tags

Sightings

Nomenclature