{"affected":[{"defaultStatus":"affected","ecosystem":"github","packageName":"libexpat/libexpat","product":"libexpat","source":"CNA: VulnCheck","vendor":"libexpat","versions":[{"lessThanOrEqual":"2.8.3","status":"affected","version":"0","versionType":"semver"}]}],"cveId":"CVE-2026-76641","cwes":["CWE-125"],"description":"Expat through 2.8.3 contains an out-of-bounds read vulnerability that allows attackers to trigger memory corruption by processing XML with external entity parsers created via XML_ExternalEntityParserCreate. A struct size mismatch between ELEMENT_TYPE members causes storeAtts to read the attIndex member past allocated memory boundaries, resulting in failure to normalize whitespace in non-CDATA attributes or a wild pointer dereference causing a segfault. This vulnerability was introduced by the fix for CVE-2026-66046.","epss":{"date":"2026-11-08","percentile":0.29229,"score":0.00353},"exploits":[],"kev":null,"metrics":[{"score":8.7,"severity":"high","source":"CNA: VulnCheck","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","version":"4.0"},{"score":7.5,"severity":"high","source":"CNA: VulnCheck","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","version":"3.1"}],"modifiedAt":1794146931881,"publishedAt":1787247070610,"references":[{"source":"CNA: VulnCheck","tags":["issue-tracking","patch"],"url":"https://github.com/libexpat/libexpat/pull/1331"},{"source":"CNA: VulnCheck","tags":["patch"],"url":"https://github.com/libexpat/libexpat/commit/98599f6dcc2b460410881fe420f5f55d6bec63bf"},{"source":"CNA: VulnCheck","tags":["third-party-advisory"],"url":"https://www.vulncheck.com/advisories/expat-out-of-bounds-read-via-dtdcopy"}],"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/1331"},{"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/98599f6dcc2b460410881fe420f5f55d6bec63bf"}],"revision":"2010416aad79e21636c4d90e221b5808bfd869c3f9055fc716218446e038b116","sources":[{"modifiedAt":1794146931881,"name":"CNA: VulnCheck","retrievedAt":1794151354325,"url":"https://www.cve.org/CVERecord?id=CVE-2026-76641"},{"modifiedAt":null,"name":"FIRST EPSS","retrievedAt":1794151368158,"url":"https://api.first.org/data/v1/epss?cve=CVE-2026-76641"}],"ssvc":{"assessedAt":1787251731305,"automatable":"yes","exploitation":"none","source":"ADP: CISA-ADP","technicalImpact":"partial"},"status":"published","title":"Expat Out-of-Bounds Read via dtdCopy","updatedAt":1794151368158}