{"id":"CVE-2026-77214","summary":"libexpat Heap Buffer Over-read in xmlparse.c via XML_ParseBuffer","details":"libexpat before commit 13c5f63 contains a heap buffer over-read vulnerability in xmlparse.c. XML_ParseBuffer advances the parse buffer end with parser-\u003em_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.","modified":"2026-10-08T02:52:01.536178772Z","published":"2026-10-07T14:35:42.794Z","database_specific":{"cna_assigner":"VulnCheck","cwe_ids":["CWE-125"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/77xxx/CVE-2026-77214.json"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/77xxx/CVE-2026-77214.json"},{"type":"PACKAGE","url":"https://github.com/libexpat/libexpat"},{"type":"FIX","url":"https://github.com/libexpat/libexpat/commit/13c5f63a7f1c52c2feee3b16a1134d4fb68e9ea0"},{"type":"REPORT","url":"https://github.com/libexpat/libexpat/pull/1393"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-77214"},{"type":"ADVISORY","url":"https://www.vulncheck.com/advisories/libexpat-heap-buffer-over-read-in-xmlparse-c-via-xml-parsebuffer"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/libexpat/libexpat","events":[{"introduced":"0"},{"last_affected":"4b3f0b06f39fb5529cead381694f8929901bc273"}],"database_specific":{"extracted_events":[{"introduced":"0"},{"last_affected":"2.8.5"}],"source":"AFFECTED_FIELD"}}],"versions":["R_2_8_5","R_2_8_4","R_2_8_3","R_2_8_2","R_2_8_1","R_2_8_0","R_2_7_5","R_2_7_4","R_2_7_3","R_2_7_2","R_2_7_1","R_2_7_0","R_2_6_4","R_2_6_3","R_2_6_2","R_2_6_1","R_2_6_0","R_2_5_0","R_2_4_9","R_2_4_8","R_2_4_7","R_2_4_6","R_2_4_5","R_2_4_4","R_2_4_3","R_2_4_2","R_2_4_1","R_2_4_0","R_2_3_0","R_2_2_10","R_2_2_9","R_2_2_8","R_2_2_7","R_2_2_6","R_2_2_5","R_2_2_4","R_2_2_3","R_2_2_2","R_2_2_1","R_2_2_0","R_2_1_1","R_2_1_0","R_2_0_1","R_2_0_0","R_1_95_8","R_1_95_7","R_1_95_6","R_1_95_5","R_1_95_4","R_1_95_3","R_1_95_2","R_1_95_0","libexpat-alpha-1","start","sourceforge_init","jclark-orig","V20000512","V19991013","V19990728","V19990709","V19990626","V1_1","V19990425","V1990307","V19990109","V19981231","V19981122","V1_0","beta4","beta3","beta2","REC1_0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-77214.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"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"}]}