Vulnerability-Lookup

Vulnerability from bitnami_vulndb

Published

2026-05-07 08:45

Modified

2026-09-08 08:34

Summary

libModSecurity3 denial of service via segfault when using t:hexDecode on single-character query strings

Details

ModSecurity is an open source, cross platform web application firewall (WAF) engine for Apache, IIS and Nginx. Libmodsecurity is one component of the ModSecurity v3 project. A segmentation fault occurs when a rule using the t:hexDecode transformation inspects a query string parameter containing a single character. An attacker can exploit this to crash worker processes, causing a denial of service. Service resumes once the attack stops as worker processes recover from the segfault. All versions before 3.0.15 of libModSecurity3 are affected. This has been patched in version 3.0.15.

JSON

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{
  "affected": [
    {
      "package": {
        "ecosystem": "Bitnami",
        "name": "modsecurity",
        "purl": "pkg:bitnami/modsecurity"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "3.0.0"
            },
            {
              "fixed": "3.0.15"
            }
          ],
          "type": "SEMVER"
        }
      ],
      "severity": [
        {
          "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/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",
          "type": "CVSS_V4"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-30923"
  ],
  "database_specific": {
    "cpes": [
      "cpe:2.3:a:trustwave:modsecurity:*:*:*:*:*:*:*:*"
    ],
    "severity": "High"
  },
  "details": "ModSecurity is an open source, cross platform web application firewall (WAF) engine for Apache, IIS and Nginx. Libmodsecurity is one component of the ModSecurity v3 project. A segmentation fault occurs when a rule using the t:hexDecode transformation inspects a query string parameter containing a single character. An attacker can exploit this to crash worker processes, causing a denial of service. Service resumes once the attack stops as worker processes recover from the segfault. All versions before 3.0.15 of libModSecurity3 are affected. This has been patched in version 3.0.15.",
  "id": "BIT-modsecurity-2026-30923",
  "modified": "2026-09-08T08:34:36.952Z",
  "published": "2026-05-07T08:45:59.405Z",
  "references": [
    {
      "type": "FIX",
      "url": "https://github.com/owasp-modsecurity/ModSecurity/releases/tag/v3.0.15"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/owasp-modsecurity/ModSecurity/security/advisories/GHSA-qrjc-3jpc-3h2g"
    },
    {
      "type": "WEB",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-30923"
    }
  ],
  "schema_version": "1.6.2",
  "summary": "libModSecurity3 denial of service via segfault when using t:hexDecode on single-character query strings"
}

CVE-2026-30923 (GCVE-0-2026-30923)

Vulnerability from cvelistv5 – Published: 2026-05-05 18:46 – Updated: 2026-05-05 19:21

Title

libModSecurity3 denial of service via segfault when using t:hexDecode on single-character query strings

Summary

Severity

8.2 (High)


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

SSVC

Exploitation: poc Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-05-05 19:20 UTC

CWE

CWE-125 - Out-of-bounds Read

Assigner

GitHub_M mitre root

References

2 references

URL	Tags
https://github.com/owasp-modsecurity/ModSecurity/…	x_refsource_CONFIRM
https://github.com/owasp-modsecurity/ModSecurity/…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
owasp-modsecurity	ModSecurity	Affected: < 3.0.15

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-30923",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-05-05T19:20:55.329784Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-05-05T19:21:08.898Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "references": [
          {
            "tags": [
              "exploit"
            ],
            "url": "https://github.com/owasp-modsecurity/ModSecurity/security/advisories/GHSA-qrjc-3jpc-3h2g"
          }
        ],
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "ModSecurity",
          "vendor": "owasp-modsecurity",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 3.0.15"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "ModSecurity is an open source, cross platform web application firewall (WAF) engine for Apache, IIS and Nginx. Libmodsecurity is one component of the ModSecurity v3 project. A segmentation fault occurs when a rule using the t:hexDecode transformation inspects a query string parameter containing a single character. An attacker can exploit this to crash worker processes, causing a denial of service. Service resumes once the attack stops as worker processes recover from the segfault. All versions before 3.0.15 of libModSecurity3 are affected. This has been patched in version 3.0.15."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "baseScore": 8.2,
            "baseSeverity": "HIGH",
            "privilegesRequired": "NONE",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
            "version": "4.0",
            "vulnAvailabilityImpact": "HIGH",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "NONE"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-125",
              "description": "CWE-125: Out-of-bounds Read",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-05T18:46:03.201Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/owasp-modsecurity/ModSecurity/security/advisories/GHSA-qrjc-3jpc-3h2g",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/owasp-modsecurity/ModSecurity/security/advisories/GHSA-qrjc-3jpc-3h2g"
        },
        {
          "name": "https://github.com/owasp-modsecurity/ModSecurity/releases/tag/v3.0.15",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/owasp-modsecurity/ModSecurity/releases/tag/v3.0.15"
        }
      ],
      "source": {
        "advisory": "GHSA-qrjc-3jpc-3h2g",
        "discovery": "UNKNOWN"
      },
      "title": "libModSecurity3 denial of service via segfault when using t:hexDecode on single-character query strings"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-30923",
    "datePublished": "2026-05-05T18:46:03.201Z",
    "dateReserved": "2026-03-07T16:40:05.884Z",
    "dateUpdated": "2026-05-05T19:21:08.898Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

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.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.