{"affected":[{"defaultStatus":"unaffected","ecosystem":"github","packageName":"libexpat/libexpat","product":"libexpat","source":"CNA: VulnCheck","vendor":"libexpat","versions":[{"lessThanOrEqual":"2.8.5","status":"affected","version":"0","versionType":"semver"},{"status":"unaffected","version":"13c5f63a7f1c52c2feee3b16a1134d4fb68e9ea0","versionType":"git"}]}],"cveId":"CVE-2026-77214","cwes":["CWE-125"],"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.","epss":{"date":"2026-11-08","percentile":0.25114,"score":0.0032},"exploits":[],"kev":null,"metrics":[{"score":8.3,"severity":"high","source":"CNA: VulnCheck","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","version":"4.0"},{"score":8.2,"severity":"high","source":"CNA: VulnCheck","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:L","version":"3.1"}],"modifiedAt":1794146934736,"publishedAt":1791383742794,"references":[{"source":"CNA: VulnCheck","tags":["issue-tracking","patch"],"url":"https://github.com/libexpat/libexpat/pull/1393"},{"source":"CNA: VulnCheck","tags":["patch"],"url":"https://github.com/libexpat/libexpat/commit/13c5f63a7f1c52c2feee3b16a1134d4fb68e9ea0"},{"source":"CNA: VulnCheck","tags":["third-party-advisory"],"url":"https://www.vulncheck.com/advisories/libexpat-heap-buffer-over-read-in-xmlparse-c-via-xml-parsebuffer"}],"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/1393"},{"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/13c5f63a7f1c52c2feee3b16a1134d4fb68e9ea0"}],"revision":"508d01d0d07578a5ce4907946aa15a9b2e5c73c65ffef1f67faedfc45d92f803","sources":[{"modifiedAt":1794146934736,"name":"CNA: VulnCheck","retrievedAt":1794151358795,"url":"https://www.cve.org/CVERecord?id=CVE-2026-77214"},{"modifiedAt":null,"name":"FIRST EPSS","retrievedAt":1794151367504,"url":"https://api.first.org/data/v1/epss?cve=CVE-2026-77214"}],"ssvc":{"assessedAt":1791599158906,"automatable":"yes","exploitation":"none","source":"ADP: CISA-ADP","technicalImpact":"partial"},"status":"published","title":"libexpat Heap Buffer Over-read in xmlparse.c via XML_ParseBuffer","updatedAt":1794151367504}