{"id":"CVE-2026-77214","title":"libexpat before commit 13c5f63 contains a heap buffer over-read vulnerability in xmlparse.c","summary":"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 a…","severity":"high","cvss":8.2,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:L","cwe":["CWE-125"],"vendor":"libexpat","product":"libexpat","affected":["libexpat <= 2.8.5"],"published":"2026-10-07","updated":"2026-10-07","sourceUpdated":"2026-10-07T15:57:20.793","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-77214","references":[{"url":"https://github.com/libexpat/libexpat/commit/13c5f63a7f1c52c2feee3b16a1134d4fb68e9ea0","label":"disclosure@vulncheck.com"},{"url":"https://github.com/libexpat/libexpat/pull/1393","label":"disclosure@vulncheck.com"},{"url":"https://www.vulncheck.com/advisories/libexpat-heap-buffer-over-read-in-xmlparse-c-via-xml-parsebuffer","label":"disclosure@vulncheck.com"}],"tags":["nvd","cve.org"],"ingestedAt":"2026-10-07T15:36:04.056Z","slug":"CVE-2026-77214","body":"## Overview\n\nlibexpat 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":45,"depthScoreParts":{"impact":45.1,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}