CVE-2026-41401 (GCVE-0-2026-41401)

Vulnerability from cvelistv5 – Published: 2026-05-26 14:08 – Updated: 2026-05-26 17:58
VLAI
Title
libyang - Heap Use-After-Free Write in XML Metadata Parsing
Summary
libyang before 5.2.6 contains a heap use-after-free write vulnerability in lyd_parser_set_data_flags that incorrectly updates metadata list pointers when freeing non-head default metadata entries. Attackers can trigger this vulnerability by submitting crafted YANG XML documents with specific metadata attributes to applications parsing untrusted XML data, causing process crashes or potential code execution.
Severity
6.9 (Medium)
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
6.5 (Medium)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
SSVC
Exploitation: poc Automatable: no Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
Assigner
References
Impacted products
Vendor Product Version
libyang libyang Affected: 0 , < 5.4.3 (custom)
Unaffected: 5.4.3 (custom)
Create a notification for this product.
Date Public
2026-03-26 00:00
Credits
kevin-valerio
Show details on NVD website
To clipboard 

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-41401",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-05-26T17:57:20.352377Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-05-26T17:58:08.114Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "references": [
          {
            "tags": [
              "exploit"
            ],
            "url": "https://github.com/CESNET/libyang/security/advisories/GHSA-9f49-8x56-jmjc"
          },
          {
            "tags": [
              "exploit"
            ],
            "url": "https://red.anthropic.com/2026/cvd/findings/ANT-2026-TZQ1KH7E"
          }
        ],
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "libyang",
          "vendor": "libyang",
          "versions": [
            {
              "lessThan": "5.4.3",
              "status": "affected",
              "version": "0",
              "versionType": "custom"
            },
            {
              "status": "unaffected",
              "version": "5.4.3",
              "versionType": "custom"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:a:cesnet:libyang:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.4.3",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "reporter",
          "value": "kevin-valerio"
        }
      ],
      "datePublic": "2026-03-26T00:00:00.000Z",
      "descriptions": [
        {
          "lang": "en",
          "value": "libyang before 5.2.6 contains a heap use-after-free write vulnerability in lyd_parser_set_data_flags that incorrectly updates metadata list pointers when freeing non-head default metadata entries. Attackers can trigger this vulnerability by submitting crafted YANG XML documents with specific metadata attributes to applications parsing untrusted XML data, causing process crashes or potential code execution."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "LOW",
            "attackRequirements": "NONE",
            "attackVector": "NETWORK",
            "baseScore": 6.9,
            "baseSeverity": "MEDIUM",
            "exploitMaturity": "NOT_DEFINED",
            "privilegesRequired": "LOW",
            "providerUrgency": "NOT_DEFINED",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "valueDensity": "NOT_DEFINED",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
            "version": "4.0",
            "vulnAvailabilityImpact": "HIGH",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "NONE",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
          },
          "format": "CVSS"
        },
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "HIGH",
            "baseScore": 6.5,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "NONE",
            "integrityImpact": "NONE",
            "privilegesRequired": "LOW",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
            "version": "3.1"
          },
          "format": "CVSS"
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-416",
              "description": "Use After Free",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-26T14:14:49.472Z",
        "orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
        "shortName": "VulnCheck"
      },
      "references": [
        {
          "name": "GHSA Advisory GHSA-9f49-8x56-jmjc",
          "tags": [
            "vendor-advisory"
          ],
          "url": "https://github.com/CESNET/libyang/security/advisories/GHSA-9f49-8x56-jmjc"
        },
        {
          "name": "https://github.com/CESNET/libyang/commit/6b5ed47ee674fbe86b31bbebc4ff26889aeff38c",
          "tags": [
            "patch"
          ],
          "url": "https://github.com/CESNET/libyang/commit/6b5ed47ee674fbe86b31bbebc4ff26889aeff38c"
        },
        {
          "name": "Anthropic CVD Finding ANT-2026-TZQ1KH7E",
          "tags": [
            "third-party-advisory"
          ],
          "url": "https://red.anthropic.com/2026/cvd/findings/ANT-2026-TZQ1KH7E"
        },
        {
          "name": "VulnCheck Advisory: libyang - Heap Use-After-Free Write in XML Metadata Parsing",
          "tags": [
            "third-party-advisory"
          ],
          "url": "https://www.vulncheck.com/advisories/libyang-heap-use-after-free-write-in-xml-metadata-parsing"
        }
      ],
      "title": "libyang - Heap Use-After-Free Write in XML Metadata Parsing",
      "x_generator": {
        "engine": "vulncheck"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
    "assignerShortName": "VulnCheck",
    "cveId": "CVE-2026-41401",
    "datePublished": "2026-05-26T14:08:48.973Z",
    "dateReserved": "2026-04-20T14:15:22.223Z",
    "dateUpdated": "2026-05-26T17:58:08.114Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-41401",
      "date": "2026-06-13",
      "epss": "0.00035",
      "percentile": "0.10763"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-41401\",\"sourceIdentifier\":\"disclosure@vulncheck.com\",\"published\":\"2026-05-26T15:16:35.660\",\"lastModified\":\"2026-05-26T19:47:48.987\",\"vulnStatus\":\"Deferred\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"libyang before 5.2.6 contains a heap use-after-free write vulnerability in lyd_parser_set_data_flags that incorrectly updates metadata list pointers when freeing non-head default metadata entries. Attackers can trigger this vulnerability by submitting crafted YANG XML documents with specific metadata attributes to applications parsing untrusted XML data, causing process crashes or potential code execution.\"}],\"metrics\":{\"cvssMetricV40\":[{\"source\":\"disclosure@vulncheck.com\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"4.0\",\"vectorString\":\"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/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\":7.1,\"baseSeverity\":\"HIGH\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"attackRequirements\":\"NONE\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"vulnConfidentialityImpact\":\"NONE\",\"vulnIntegrityImpact\":\"NONE\",\"vulnAvailabilityImpact\":\"HIGH\",\"subConfidentialityImpact\":\"NONE\",\"subIntegrityImpact\":\"NONE\",\"subAvailabilityImpact\":\"NONE\",\"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\"}}],\"cvssMetricV31\":[{\"source\":\"disclosure@vulncheck.com\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H\",\"baseScore\":6.5,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":2.8,\"impactScore\":3.6}]},\"weaknesses\":[{\"source\":\"disclosure@vulncheck.com\",\"type\":\"Secondary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-416\"}]}],\"references\":[{\"url\":\"https://github.com/CESNET/libyang/commit/6b5ed47ee674fbe86b31bbebc4ff26889aeff38c\",\"source\":\"disclosure@vulncheck.com\"},{\"url\":\"https://github.com/CESNET/libyang/security/advisories/GHSA-9f49-8x56-jmjc\",\"source\":\"disclosure@vulncheck.com\"},{\"url\":\"https://red.anthropic.com/2026/cvd/findings/ANT-2026-TZQ1KH7E\",\"source\":\"disclosure@vulncheck.com\"},{\"url\":\"https://www.vulncheck.com/advisories/libyang-heap-use-after-free-write-in-xml-metadata-parsing\",\"source\":\"disclosure@vulncheck.com\"},{\"url\":\"https://github.com/CESNET/libyang/security/advisories/GHSA-9f49-8x56-jmjc\",\"source\":\"134c704f-9b21-4f2e-91b3-4a467353bcc0\"},{\"url\":\"https://red.anthropic.com/2026/cvd/findings/ANT-2026-TZQ1KH7E\",\"source\":\"134c704f-9b21-4f2e-91b3-4a467353bcc0\"}]}}",
    "vulnrichment": {
      "containers": "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-41401\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"poc\"}, {\"Automatable\": \"no\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-05-26T17:57:20.352377Z\"}}}], \"references\": [{\"url\": \"https://github.com/CESNET/libyang/security/advisories/GHSA-9f49-8x56-jmjc\", \"tags\": [\"exploit\"]}, {\"url\": \"https://red.anthropic.com/2026/cvd/findings/ANT-2026-TZQ1KH7E\", \"tags\": [\"exploit\"]}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-05-26T17:56:42.716Z\"}}], \"cna\": {\"title\": \"libyang - Heap Use-After-Free Write in XML Metadata Parsing\", \"credits\": [{\"lang\": \"en\", \"type\": \"reporter\", \"value\": \"kevin-valerio\"}], \"metrics\": [{\"format\": \"CVSS\", \"cvssV4_0\": {\"Safety\": \"NOT_DEFINED\", \"version\": \"4.0\", \"Recovery\": \"NOT_DEFINED\", \"baseScore\": 6.9, \"Automatable\": \"NOT_DEFINED\", \"attackVector\": \"NETWORK\", \"baseSeverity\": \"MEDIUM\", \"valueDensity\": \"NOT_DEFINED\", \"vectorString\": \"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N\", \"exploitMaturity\": \"NOT_DEFINED\", \"providerUrgency\": \"NOT_DEFINED\", \"userInteraction\": \"NONE\", \"attackComplexity\": \"LOW\", \"attackRequirements\": \"NONE\", \"privilegesRequired\": \"LOW\", \"subIntegrityImpact\": \"NONE\", \"vulnIntegrityImpact\": \"NONE\", \"subAvailabilityImpact\": \"NONE\", \"vulnAvailabilityImpact\": \"HIGH\", \"subConfidentialityImpact\": \"NONE\", \"vulnConfidentialityImpact\": \"NONE\", \"vulnerabilityResponseEffort\": \"NOT_DEFINED\"}}, {\"format\": \"CVSS\", \"cvssV3_1\": {\"scope\": \"UNCHANGED\", \"version\": \"3.1\", \"baseScore\": 6.5, \"attackVector\": \"NETWORK\", \"baseSeverity\": \"MEDIUM\", \"vectorString\": \"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H\", \"integrityImpact\": \"NONE\", \"userInteraction\": \"NONE\", \"attackComplexity\": \"LOW\", \"availabilityImpact\": \"HIGH\", \"privilegesRequired\": \"LOW\", \"confidentialityImpact\": \"NONE\"}}], \"affected\": [{\"vendor\": \"libyang\", \"product\": \"libyang\", \"versions\": [{\"status\": \"affected\", \"version\": \"0\", \"lessThan\": \"5.4.3\", \"versionType\": \"custom\"}, {\"status\": \"unaffected\", \"version\": \"5.4.3\", \"versionType\": \"custom\"}], \"defaultStatus\": \"unaffected\"}], \"datePublic\": \"2026-03-26T00:00:00.000Z\", \"references\": [{\"url\": \"https://github.com/CESNET/libyang/security/advisories/GHSA-9f49-8x56-jmjc\", \"name\": \"GHSA Advisory GHSA-9f49-8x56-jmjc\", \"tags\": [\"vendor-advisory\"]}, {\"url\": \"https://github.com/CESNET/libyang/commit/6b5ed47ee674fbe86b31bbebc4ff26889aeff38c\", \"name\": \"https://github.com/CESNET/libyang/commit/6b5ed47ee674fbe86b31bbebc4ff26889aeff38c\", \"tags\": [\"patch\"]}, {\"url\": \"https://red.anthropic.com/2026/cvd/findings/ANT-2026-TZQ1KH7E\", \"name\": \"Anthropic CVD Finding ANT-2026-TZQ1KH7E\", \"tags\": [\"third-party-advisory\"]}, {\"url\": \"https://www.vulncheck.com/advisories/libyang-heap-use-after-free-write-in-xml-metadata-parsing\", \"name\": \"VulnCheck Advisory: libyang - Heap Use-After-Free Write in XML Metadata Parsing\", \"tags\": [\"third-party-advisory\"]}], \"x_generator\": {\"engine\": \"vulncheck\"}, \"descriptions\": [{\"lang\": \"en\", \"value\": \"libyang before 5.2.6 contains a heap use-after-free write vulnerability in lyd_parser_set_data_flags that incorrectly updates metadata list pointers when freeing non-head default metadata entries. Attackers can trigger this vulnerability by submitting crafted YANG XML documents with specific metadata attributes to applications parsing untrusted XML data, causing process crashes or potential code execution.\"}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-416\", \"description\": \"Use After Free\"}]}], \"cpeApplicability\": [{\"nodes\": [{\"negate\": false, \"cpeMatch\": [{\"criteria\": \"cpe:2.3:a:cesnet:libyang:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"5.4.3\"}], \"operator\": \"OR\"}]}], \"providerMetadata\": {\"orgId\": \"83251b91-4cc7-4094-a5c7-464a1b83ea10\", \"shortName\": \"VulnCheck\", \"dateUpdated\": \"2026-05-26T14:14:49.472Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-41401\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-05-26T17:58:08.114Z\", \"dateReserved\": \"2026-04-20T14:15:22.223Z\", \"assignerOrgId\": \"83251b91-4cc7-4094-a5c7-464a1b83ea10\", \"datePublished\": \"2026-05-26T14:08:48.973Z\", \"assignerShortName\": \"VulnCheck\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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.