{
  "containers": {
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      "affected": [
        {
          "defaultStatus": "unaffected",
          "packageURL": "pkg:github/libexpat/libexpat",
          "product": "libexpat",
          "repo": "https://github.com/libexpat/libexpat",
          "vendor": "libexpat",
          "versions": [
            {
              "lessThanOrEqual": "2.9.0",
              "status": "affected",
              "version": "0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:a:libexpat_project:libexpat:*:*:*:*:*:*:*:*",
                  "versionEndIncluding": "2.9.0",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "Mirko Swillus"
        },
        {
          "lang": "en",
          "type": "remediation developer",
          "value": "Sebastian Pipping"
        }
      ],
      "datePublic": "2026-10-27T00:00:00.000Z",
      "descriptions": [
        {
          "lang": "en",
          "value": "libexpat through 2.9.0 contains a signed integer overflow vulnerability in storeAtts() in lib/xmlparse.c that allows attackers to trigger out-of-bounds writes via oversized attribute counts. Attackers can supply a multi-gigabyte document with a start tag carrying over 2^30 attributes to overflow attIndex and nPrefixes, crashing applications or corrupting heap memory."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "HIGH",
            "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:H/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"
          },
          "format": "CVSS"
        },
        {
          "cvssV3_1": {
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            "attackVector": "NETWORK",
            "availabilityImpact": "HIGH",
            "baseScore": 5.9,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "NONE",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H",
            "version": "3.1"
          },
          "format": "CVSS"
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-190",
              "description": "Integer Overflow or Wraparound",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-28T02:03:19.447Z",
        "orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
        "shortName": "VulnCheck"
      },
      "references": [
        {
          "tags": [
            "patch",
            "issue-tracking"
          ],
          "url": "https://github.com/libexpat/libexpat/pull/1450"
        },
        {
          "tags": [
            "patch"
          ],
          "url": "https://github.com/libexpat/libexpat/commit/1bac53c4fc460a03cd9860f39501c7979f6750ae"
        },
        {
          "tags": [
            "patch"
          ],
          "url": "https://github.com/libexpat/libexpat/commit/621cb2c78b253ee023a86bc91d6ddb048481c04c"
        },
        {
          "tags": [
            "technical-description"
          ],
          "url": "https://github.com/libexpat/libexpat/blob/a76b1174c1ea52abb639a4c69d52b630a8a106a2/expat/lib/xmlparse.c#L4138-L4140"
        },
        {
          "tags": [
            "product"
          ],
          "url": "https://github.com/libexpat/libexpat"
        },
        {
          "name": "VulnCheck Advisory: libexpat through 2.9.0 Integer Overflow in storeAtts via attIndex and nPrefixes",
          "tags": [
            "third-party-advisory"
          ],
          "url": "https://www.vulncheck.com/advisories/libexpat-through-2.9.0-integer-overflow-in-storeatts-via-attindex-and-nprefixes"
        }
      ],
      "title": "libexpat through 2.9.0 Integer Overflow in storeAtts via attIndex and nPrefixes",
      "x_generator": {
        "engine": "vulncheck-endgame"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
    "assignerShortName": "VulnCheck",
    "cveId": "CVE-2026-118370",
    "datePublished": "2026-10-28T02:03:19.447Z",
    "dateReserved": "2026-10-28T01:19:19.454Z",
    "dateUpdated": "2026-10-28T02:03:19.447Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}