{"affected":[{"defaultStatus":"unaffected","ecosystem":"github","packageName":"libexpat/libexpat","product":"libexpat","source":"CNA: VulnCheck","vendor":"libexpat","versions":[{"lessThan":"2.8.5","status":"affected","version":"0","versionType":"semver"},{"status":"unaffected","version":"2.8.5","versionType":"semver"}]}],"cveId":"CVE-2026-93990","cwes":["CWE-176"],"description":"Expat before 2.8.5 fails to validate that a high surrogate in UTF-16 input is followed by a low surrogate, allowing malformed UTF-16 sequences to be accepted. Attackers can supply UTF-16 encoded XML containing lone high surrogates that consume the following code unit, causing Expat to pass unpaired surrogates to applications built with XML_UNICODE and to silently replace input characters in other builds.","epss":{"date":"2026-11-08","percentile":0.34853,"score":0.00403},"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:H/VA:N/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:H/A:N","version":"3.1"}],"modifiedAt":1794146962450,"publishedAt":1789858691224,"references":[{"source":"CNA: VulnCheck","tags":["issue-tracking","patch"],"url":"https://github.com/libexpat/libexpat/pull/1282"},{"source":"CNA: VulnCheck","tags":["patch"],"url":"https://github.com/libexpat/libexpat/commit/ff6e1d7e750bbe245178f51a47a965dc8342861a"},{"source":"CNA: VulnCheck","tags":["release-notes"],"url":"https://github.com/libexpat/libexpat/releases/tag/R_2_8_5"},{"source":"CNA: VulnCheck","tags":["vendor-advisory"],"url":"https://blog.hartwork.org/posts/expat-2-8-5-released/"},{"source":"CNA: VulnCheck","tags":["product"],"url":"https://github.com/libexpat/libexpat"},{"source":"CNA: VulnCheck","tags":["third-party-advisory"],"url":"https://www.vulncheck.com/advisories/expat-through-2.8.4-malformed-utf-16-acceptance-via-unchecked-surrogate"}],"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/1282"},{"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/ff6e1d7e750bbe245178f51a47a965dc8342861a"}],"revision":"137f03f4ac460f1d09b27c2406de31c342e515a5738e441c10ee979fa1577333","sources":[{"modifiedAt":1794146962450,"name":"CNA: VulnCheck","retrievedAt":1794151407160,"url":"https://www.cve.org/CVERecord?id=CVE-2026-93990"},{"modifiedAt":null,"name":"FIRST EPSS","retrievedAt":1794151407596,"url":"https://api.first.org/data/v1/epss?cve=CVE-2026-93990"}],"ssvc":{"assessedAt":1790003443564,"automatable":"yes","exploitation":"none","source":"ADP: CISA-ADP","technicalImpact":"partial"},"status":"published","title":"Expat before 2.8.5 Malformed UTF-16 Acceptance via Unchecked Surrogate","updatedAt":1794151407596}