{"affected":[{"defaultStatus":"unaffected","ecosystem":"github","packageName":"libexpat/libexpat","product":"libexpat","source":"CNA: VulnCheck","vendor":"libexpat","versions":[{"lessThanOrEqual":"2.9.0","status":"affected","version":"0","versionType":"semver"}]}],"cpeConfigurations":[{"negate":false,"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:a:libexpat_project:libexpat:*:*:*:*:*:*:*:*","versionEndIncluding":"2.9.0","vulnerable":true}],"negate":false,"operator":"OR"}],"operator":"OR"}],"cveId":"CVE-2026-118370","cwes":["CWE-190"],"description":"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.","epss":{"date":"2026-11-02","percentile":0.38418,"score":0.00442},"exploits":[],"kev":null,"metrics":[{"score":8.2,"severity":"high","source":"CNA: VulnCheck","vector":"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"},{"score":5.9,"severity":"medium","source":"CNA: VulnCheck","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H","version":"3.1"},{"score":8.2,"severity":"high","source":"NVD: disclosure@vulncheck.com","vector":"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/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"},{"score":8.2,"severity":"high","source":"NVD: nvd@nist.gov","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H","version":"3.1"},{"score":5.9,"severity":"medium","source":"NVD: disclosure@vulncheck.com","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H","version":"3.1"}],"modifiedAt":1793649383246,"publishedAt":1793152999447,"references":[{"source":"CNA: VulnCheck","tags":["patch","issue-tracking"],"url":"https://github.com/libexpat/libexpat/pull/1450"},{"source":"CNA: VulnCheck","tags":["patch"],"url":"https://github.com/libexpat/libexpat/commit/1bac53c4fc460a03cd9860f39501c7979f6750ae"},{"source":"CNA: VulnCheck","tags":["patch"],"url":"https://github.com/libexpat/libexpat/commit/621cb2c78b253ee023a86bc91d6ddb048481c04c"},{"source":"CNA: VulnCheck","tags":["technical-description"],"url":"https://github.com/libexpat/libexpat/blob/a76b1174c1ea52abb639a4c69d52b630a8a106a2/expat/lib/xmlparse.c#L4138-L4140"},{"source":"CNA: VulnCheck","tags":["product"],"url":"https://github.com/libexpat/libexpat"},{"source":"CNA: VulnCheck","tags":["third-party-advisory"],"url":"https://www.vulncheck.com/advisories/libexpat-through-2.9.0-integer-overflow-in-storeatts-via-attindex-and-nprefixes"},{"source":"disclosure@vulncheck.com","tags":["Product"],"url":"https://github.com/libexpat/libexpat"},{"source":"disclosure@vulncheck.com","tags":["Product"],"url":"https://github.com/libexpat/libexpat/blob/a76b1174c1ea52abb639a4c69d52b630a8a106a2/expat/lib/xmlparse.c#L4138-L4140"},{"source":"disclosure@vulncheck.com","tags":["Patch"],"url":"https://github.com/libexpat/libexpat/commit/1bac53c4fc460a03cd9860f39501c7979f6750ae"},{"source":"disclosure@vulncheck.com","tags":["Patch"],"url":"https://github.com/libexpat/libexpat/commit/621cb2c78b253ee023a86bc91d6ddb048481c04c"},{"source":"disclosure@vulncheck.com","tags":["Patch"],"url":"https://github.com/libexpat/libexpat/pull/1450"},{"source":"disclosure@vulncheck.com","tags":["Patch","Third Party Advisory"],"url":"https://www.vulncheck.com/advisories/libexpat-through-2.9.0-integer-overflow-in-storeatts-via-attindex-and-nprefixes"}],"remediation":[{"kind":"fix","source":"CNA: VulnCheck","text":"The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches.","url":"https://github.com/libexpat/libexpat/pull/1450"},{"kind":"fix","source":"CNA: VulnCheck","text":"The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches.","url":"https://github.com/libexpat/libexpat/commit/1bac53c4fc460a03cd9860f39501c7979f6750ae"},{"kind":"fix","source":"CNA: VulnCheck","text":"The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches.","url":"https://github.com/libexpat/libexpat/commit/621cb2c78b253ee023a86bc91d6ddb048481c04c"},{"kind":"fix","source":"disclosure@vulncheck.com","text":"The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches.","url":"https://github.com/libexpat/libexpat/commit/1bac53c4fc460a03cd9860f39501c7979f6750ae"},{"kind":"fix","source":"disclosure@vulncheck.com","text":"The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches.","url":"https://github.com/libexpat/libexpat/commit/621cb2c78b253ee023a86bc91d6ddb048481c04c"},{"kind":"fix","source":"disclosure@vulncheck.com","text":"The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches.","url":"https://github.com/libexpat/libexpat/pull/1450"},{"kind":"fix","source":"disclosure@vulncheck.com","text":"The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches.","url":"https://www.vulncheck.com/advisories/libexpat-through-2.9.0-integer-overflow-in-storeatts-via-attindex-and-nprefixes"}],"revision":"f9be18f526386e44dc70f5babe46555ee43befd8cc012db00fe330f7ced7ce7d","sources":[{"modifiedAt":1793649383246,"name":"CNA: VulnCheck","retrievedAt":1793650261947,"url":"https://www.cve.org/CVERecord?id=CVE-2026-118370"},{"modifiedAt":1793633710980,"name":"NVD","retrievedAt":1793643457237,"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-118370"},{"modifiedAt":null,"name":"FIRST EPSS","retrievedAt":1793650305870,"url":"https://api.first.org/data/v1/epss?cve=CVE-2026-118370"}],"ssvc":{"assessedAt":1793649373049,"automatable":"no","exploitation":"none","source":"ADP: CISA-ADP","technicalImpact":"partial"},"status":"published","title":"libexpat through 2.9.0 Integer Overflow in storeAtts via attIndex and nPrefixes","updatedAt":1793650305870}