{"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": "2026-09-21T15:13:37.622Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10", "shortName": "VulnCheck", "dateUpdated": "2026-09-19T22:58:11.224Z"}, "datePublic": "2026-09-18T00:00:00.000Z", "title": "Expat through 2.8.4 Malformed UTF-16 Acceptance via Unchecked Surrogate", "descriptions": [{"lang": "en", "value": "Expat through 2.8.4 fails to validate low surrogates following high surrogates in UTF-16 input, allowing malformed UTF-16 sequences to be accepted. Attackers can craft UTF-16 encoded XML with lone high surrogates that consume following code units, hiding markup characters from the parser and enabling XML injection attacks."}], "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", "lessThanOrEqual": "2.8.4"}]}], "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:libexpat_project:libexpat:*:*:*:*:*:*:*:*", "versionEndIncluding": "2.8.4"}]}]}], "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", "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"}}]}}

{"dataType": "CVE_RECORD", "containers": {"adp": [{"title": "CISA ADP Vulnrichment", "metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2026-93990", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "yes"}, {"Technical Impact": "partial"}], "version": "2.0.3", "timestamp": "2026-09-21T15:10:43.564847Z"}}}], "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-09-21T15:11:05.367Z"}}], "cna": {"title": "Expat through 2.8.4 Malformed UTF-16 Acceptance via Unchecked Surrogate", "credits": [{"lang": "en", "type": "finder", "value": "Kartik Kenchi (netliomax25-code)"}], "metrics": [{"format": "CVSS", "cvssV4_0": {"version": "4.0", "baseScore": 8.7, "attackVector": "NETWORK", "baseSeverity": "HIGH", "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", "userInteraction": "NONE", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "subIntegrityImpact": "NONE", "vulnIntegrityImpact": "HIGH", "subAvailabilityImpact": "NONE", "vulnAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "vulnConfidentialityImpact": "NONE"}}, {"format": "CVSS", "cvssV3_1": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 7.5, "attackVector": "NETWORK", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N", "integrityImpact": "HIGH", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "NONE", "privilegesRequired": "NONE", "confidentialityImpact": "NONE"}}], "affected": [{"repo": "https://github.com/libexpat/libexpat", "vendor": "libexpat", "product": "libexpat", "versions": [{"status": "affected", "version": "0", "versionType": "semver", "lessThanOrEqual": "2.8.4"}], "packageURL": "pkg:github/libexpat/libexpat", "defaultStatus": "unaffected"}], "datePublic": "2026-09-18T00:00:00.000Z", "references": [{"url": "https://github.com/libexpat/libexpat/pull/1282", "name": "GitHub PR #1282", "tags": ["issue-tracking", "patch"]}, {"url": "https://github.com/libexpat/libexpat/commit/ff6e1d7e750bbe245178f51a47a965dc8342861a", "tags": ["patch"]}, {"url": "https://github.com/libexpat/libexpat", "tags": ["product"]}, {"url": "https://www.vulncheck.com/advisories/expat-through-2.8.4-malformed-utf-16-acceptance-via-unchecked-surrogate", "name": "VulnCheck Advisory: Expat through 2.8.4 Malformed UTF-16 Acceptance via Unchecked Surrogate", "tags": ["third-party-advisory"]}], "x_generator": {"engine": "vulncheck-endgame"}, "descriptions": [{"lang": "en", "value": "Expat through 2.8.4 fails to validate low surrogates following high surrogates in UTF-16 input, allowing malformed UTF-16 sequences to be accepted. Attackers can craft UTF-16 encoded XML with lone high surrogates that consume following code units, hiding markup characters from the parser and enabling XML injection attacks."}], "problemTypes": [{"descriptions": [{"lang": "en", "type": "CWE", "cweId": "CWE-176", "description": "Improper Handling of Unicode Encoding"}]}], "cpeApplicability": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:libexpat_project:libexpat:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndIncluding": "2.8.4"}], "operator": "OR"}]}], "providerMetadata": {"orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10", "shortName": "VulnCheck", "dateUpdated": "2026-09-19T22:58:11.224Z"}}}, "cveMetadata": {"cveId": "CVE-2026-93990", "state": "PUBLISHED", "dateUpdated": "2026-09-21T15:13:37.622Z", "dateReserved": "2026-09-19T10:55:49.093Z", "assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10", "datePublished": "2026-09-19T22:58:11.224Z", "assignerShortName": "VulnCheck"}, "dataVersion": "5.2"}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "packageURL": "pkg:github/libexpat/libexpat", "product": "libexpat", "repo": "https://github.com/libexpat/libexpat", "vendor": "libexpat", "versions": [{"lessThanOrEqual": "2.8.4", "status": "affected", "version": "0", "versionType": "semver"}]}], "source": "disclosure@vulncheck.com"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "Expat through 2.8.4 fails to validate low surrogates following high surrogates in UTF-16 input, allowing malformed UTF-16 sequences to be accepted. Attackers can craft UTF-16 encoded XML with lone high surrogates that consume following code units, hiding markup characters from the parser and enabling XML injection attacks."}], "id": "CVE-2026-93990", "lastModified": "2026-09-22T20:25:55.870", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 7.5, "baseSeverity": "HIGH", "confidentialityImpact": "NONE", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 3.6, "source": "disclosure@vulncheck.com", "type": "Secondary"}], "cvssMetricV40": [{"cvssData": {"Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "LOW", "attackRequirements": "NONE", "attackVector": "NETWORK", "availabilityRequirement": "NOT_DEFINED", "baseScore": 8.7, "baseSeverity": "HIGH", "confidentialityRequirement": "NOT_DEFINED", "exploitMaturity": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "privilegesRequired": "NONE", "providerUrgency": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "userInteraction": "NONE", "valueDensity": "NOT_DEFINED", "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/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", "vulnAvailabilityImpact": "NONE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "HIGH", "vulnerabilityResponseEffort": "NOT_DEFINED"}, "source": "disclosure@vulncheck.com", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-93990", "options": [{"exploitation": "none"}, {"automatable": "yes"}, {"technicalImpact": "partial"}], "role": "CISA Coordinator", "timestamp": "2026-09-21T15:10:43.564847Z", "version": "2.0.3"}}]}, "published": "2026-09-19T23:17:10.203", "references": [{"source": "disclosure@vulncheck.com", "url": "https://github.com/libexpat/libexpat"}, {"source": "disclosure@vulncheck.com", "url": "https://github.com/libexpat/libexpat/commit/ff6e1d7e750bbe245178f51a47a965dc8342861a"}, {"source": "disclosure@vulncheck.com", "url": "https://github.com/libexpat/libexpat/pull/1282"}, {"source": "disclosure@vulncheck.com", "url": "https://www.vulncheck.com/advisories/expat-through-2.8.4-malformed-utf-16-acceptance-via-unchecked-surrogate"}], "sourceIdentifier": "disclosure@vulncheck.com", "vulnStatus": "Awaiting Analysis", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-176"}], "source": "disclosure@vulncheck.com", "type": "Secondary"}]}

{"bugzilla": {"description": "expat: Expat: XML Injection via Malformed UTF-16 Input", "id": "2538967", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2538967"}, "csaw": false, "cvss3": {"cvss3_base_score": "7.5", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N", "status": "draft"}, "cwe": "CWE-91", "details": ["Expat through 2.8.4 fails to validate low surrogates following high surrogates in UTF-16 input, allowing malformed UTF-16 sequences to be accepted. Attackers can craft UTF-16 encoded XML with lone high surrogates that consume following code units, hiding markup characters from the parser and enabling XML injection attacks.", "A flaw was found in Expat. This vulnerability allows a remote attacker to send specially crafted UTF-16 encoded XML data. Due to improper validation of surrogate characters, the parser can be tricked into accepting malformed sequences, which can hide legitimate markup characters. This could enable XML injection attacks, potentially leading to information disclosure or other integrity impacts."], "name": "CVE-2026-93990", "package_state": [{"cpe": "cpe:/a:redhat:openshift:4", "fix_state": "Affected", "package_name": "openshift/ose-rhel-coreos-8", "product_name": "Red Hat OpenShift Container Platform 4"}, {"cpe": "cpe:/a:redhat:openshift:4", "fix_state": "Affected", "package_name": "openshift/ose-rhel-coreos-9", "product_name": "Red Hat OpenShift Container Platform 4"}], "public_date": "2026-09-19T22:58:11Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-93990\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-93990\nhttps://github.com/libexpat/libexpat\nhttps://github.com/libexpat/libexpat/commit/ff6e1d7e750bbe245178f51a47a965dc8342861a\nhttps://github.com/libexpat/libexpat/pull/1282\nhttps://www.vulncheck.com/advisories/expat-through-2.8.4-malformed-utf-16-acceptance-via-unchecked-surrogate"], "threat_severity": "Important"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[0,2.8.4]"}}], "enrichment": {"confidence": 90.0, "confidence_source": "matching", "scores": [{"score": 90.0, "source": "matching"}]}, "original": {"product": "libexpat", "source": "cna", "vendor": "libexpat"}, "product": "expat", "vendor": "libexpat"}], "created": "2026-09-20T01:15:07.030187+00:00", "updated": "2026-09-23T02:15:17.407005+00:00", "vendors": ["libexpat", "libexpat$PRODUCT$expat"]}