{"id":"CVE-2026-77214","state":"PUBLISHED","title":"libexpat Heap Buffer Over-read in xmlparse.c via XML_ParseBuffer","description":"libexpat before commit 13c5f63 contains a heap buffer over-read vulnerability in xmlparse.c. XML_ParseBuffer advances the parse buffer end with parser->m_bufferEnd += len using a caller-supplied length that is not validated against the allocated buffer size, so repeated XML_ParseBuffer calls move m_bufferEnd past the end of the heap allocation and subsequent parsing reads out of bounds. Reaching this path requires a parse buffer to already be present; otherwise XML_ParseBuffer returns XML_ERROR_NO_BUFFER. A buffer is present after a prior call to XML_GetBuffer, either directly (the common case) or indirectly through a prior XML_Parse call that allocates the buffer internally. The over-read discloses adjacent heap memory to the calling application, recovering heap pointers, libc function pointers, and code pointers sufficient to defeat ASLR and build further exploitation primitives.","publishedAt":"2026-10-07T14:35:42.794Z","updatedAt":"2026-10-27T10:14:34.918Z","severity":{"score":8.3,"label":"High","version":"4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:L/SC:N/SI:N/SA:N","source":"VulnCheck"},"assigner":"VulnCheck","products":["libexpat libexpat"],"affected":[{"vendor":"libexpat","product":"libexpat","packageURL":"pkg:github/libexpat/libexpat","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThanOrEqual":"2.8.5","versionType":"semver"},{"version":"13c5f63a7f1c52c2feee3b16a1134d4fb68e9ea0","status":"unaffected","versionType":"git"}],"repo":"https://github.com/libexpat/libexpat"}],"references":["https://github.com/libexpat/libexpat/pull/1393","https://github.com/libexpat/libexpat/commit/13c5f63a7f1c52c2feee3b16a1134d4fb68e9ea0","https://www.vulncheck.com/advisories/libexpat-heap-buffer-over-read-in-xmlparse-c-via-xml-parsebuffer"],"weaknesses":["CWE-125"],"ingestedAt":"2026-10-29T20:13:07.220Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/77xxx/CVE-2026-77214.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-77214","state":"PUBLISHED","datePublished":"2026-10-07T14:35:42.794Z","dateUpdated":"2026-10-27T10:14:34.918Z","assignerShortName":"VulnCheck","assignerOrgId":"83251b91-4cc7-4094-a5c7-464a1b83ea10","dateReserved":"2026-08-20T18:25:46.943Z"},"containers":{"cna":{"title":"libexpat Heap Buffer Over-read in xmlparse.c via XML_ParseBuffer","descriptions":[{"lang":"en","value":"libexpat before commit 13c5f63 contains a heap buffer over-read vulnerability in xmlparse.c. XML_ParseBuffer advances the parse buffer end with parser->m_bufferEnd += len using a caller-supplied length that is not validated against the allocated buffer size, so repeated XML_ParseBuffer calls move m_bufferEnd past the end of the heap allocation and subsequent parsing reads out of bounds. Reaching this path requires a parse buffer to already be present; otherwise XML_ParseBuffer returns XML_ERROR_NO_BUFFER. A buffer is present after a prior call to XML_GetBuffer, either directly (the common case) or indirectly through a prior XML_Parse call that allocates the buffer internally. The over-read discloses adjacent heap memory to the calling application, recovering heap pointers, libc function pointers, and code pointers sufficient to defeat ASLR and build further exploitation primitives."}],"affected":[{"vendor":"libexpat","product":"libexpat","packageURL":"pkg:github/libexpat/libexpat","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThanOrEqual":"2.8.5","versionType":"semver"},{"version":"13c5f63a7f1c52c2feee3b16a1134d4fb68e9ea0","status":"unaffected","versionType":"git"}],"repo":"https://github.com/libexpat/libexpat"}],"references":[{"url":"https://github.com/libexpat/libexpat/pull/1393","name":"Pull Request","tags":["issue-tracking"]},{"url":"https://github.com/libexpat/libexpat/commit/13c5f63a7f1c52c2feee3b16a1134d4fb68e9ea0","name":"Patch Commit","tags":["patch"]},{"url":"https://www.vulncheck.com/advisories/libexpat-heap-buffer-over-read-in-xmlparse-c-via-xml-parsebuffer","tags":["third-party-advisory"]}],"metrics":[{"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}],"cvssV4_0":{"attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"PRESENT","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"HIGH","subConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE","subIntegrityImpact":"NONE","vulnAvailabilityImpact":"LOW","subAvailabilityImpact":"NONE","exploitMaturity":"NOT_DEFINED","Safety":"NOT_DEFINED","Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","valueDensity":"NOT_DEFINED","vulnerabilityResponseEffort":"NOT_DEFINED","providerUrgency":"NOT_DEFINED","version":"4.0","baseSeverity":"HIGH","baseScore":8.3,"vectorString":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:L/SC:N/SI:N/SA:N"}},{"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}],"cvssV3_1":{"attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"NONE","availabilityImpact":"LOW","version":"3.1","baseSeverity":"HIGH","baseScore":8.2,"vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:L"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-125","lang":"en","description":"Out-of-bounds Read","type":"CWE"}]}],"providerMetadata":{"shortName":"VulnCheck","orgId":"83251b91-4cc7-4094-a5c7-464a1b83ea10","dateUpdated":"2026-10-27T10:14:34.918Z"},"tags":["x_open-source"],"datePublic":"2026-09-24T00:00:00.000Z","credits":[{"lang":"en","value":"Fabian Wahle (Hap Security)","type":"finder"},{"lang":"en","value":"Filippo Tedeschi","type":"finder"},{"lang":"en","value":"VulnCheck","type":"coordinator"}],"source":{"discovery":"UNKNOWN"},"x_generator":{"engine":"vulncheck"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:a:libexpat_project:libexpat:*:*:*:*:*:*:*:*","versionEndIncluding":"2.8.5"}]}]}]},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-10-10T02:25:58.906885Z","id":"CVE-2026-77214","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-10T02:26:09.470Z"}}]}}}