{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-93990","assignerOrgId":"83251b91-4cc7-4094-a5c7-464a1b83ea10","state":"PUBLISHED","assignerShortName":"VulnCheck","dateReserved":"2026-09-19T10:55:49.093Z","datePublished":"2026-09-19T22:58:11.224Z","dateUpdated":"2026-09-28T16:11:06.770Z"},"containers":{"cna":{"providerMetadata":{"orgId":"83251b91-4cc7-4094-a5c7-464a1b83ea10","shortName":"VulnCheck","dateUpdated":"2026-09-28T16:11:06.770Z"},"datePublic":"2026-09-18T00:00:00.000Z","title":"Expat before 2.8.5 Malformed UTF-16 Acceptance via Unchecked Surrogate","descriptions":[{"lang":"en","value":"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."}],"problemTypes":[{"descriptions":[{"lang":"en","description":"Improper Handling of Unicode Encoding","cweId":"CWE-176","type":"CWE"}]}],"affected":[{"vendor":"libexpat","product":"libexpat","defaultStatus":"unaffected","packageURL":"pkg:github/libexpat/libexpat","repo":"https://github.com/libexpat/libexpat","versions":[{"version":"0","status":"affected","versionType":"semver","lessThan":"2.8.5"},{"version":"2.8.5","status":"unaffected","versionType":"semver"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:a:libexpat_project:libexpat:*:*:*:*:*:*:*:*","versionEndExcluding":"2.8.5"}]}]}],"metrics":[{"format":"CVSS","cvssV4_0":{"version":"4.0","vectorString":"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","attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"NONE","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"HIGH","vulnAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","subAvailabilityImpact":"NONE","baseScore":8.7,"baseSeverity":"HIGH"}},{"format":"CVSS","cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"HIGH","availabilityImpact":"NONE","baseScore":7.5,"baseSeverity":"HIGH"}}],"references":[{"url":"https://github.com/libexpat/libexpat/pull/1282","tags":["issue-tracking","patch"],"name":"GitHub PR #1282"},{"url":"https://github.com/libexpat/libexpat/commit/ff6e1d7e750bbe245178f51a47a965dc8342861a","tags":["patch"]},{"url":"https://github.com/libexpat/libexpat/releases/tag/R_2_8_5","tags":["release-notes"]},{"url":"https://blog.hartwork.org/posts/expat-2-8-5-released/","tags":["vendor-advisory"]},{"url":"https://github.com/libexpat/libexpat","tags":["product"]},{"name":"VulnCheck Advisory: Expat through 2.8.4 Malformed UTF-16 Acceptance via Unchecked Surrogate","tags":["third-party-advisory"],"url":"https://www.vulncheck.com/advisories/expat-through-2.8.4-malformed-utf-16-acceptance-via-unchecked-surrogate"}],"credits":[{"lang":"en","value":"Kartik Kenchi (netliomax25-code)","type":"finder"}],"x_generator":{"engine":"vulncheck-endgame"}},"adp":[{"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-09-21T15:10:43.564847Z","id":"CVE-2026-93990","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-09-21T15:13:37.622Z"}}]}}