{"id":"CVE-2026-77214","published":"2026-10-07T15:17:53.327","lastModified":"2026-10-10T03:17:08.487","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.","cvssScore":8.2,"cvssSeverity":"HIGH","cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:L","cwes":["CWE-125"],"vendors":[],"products":[],"references":[{"url":"https://github.com/libexpat/libexpat/commit/13c5f63a7f1c52c2feee3b16a1134d4fb68e9ea0","tags":[]},{"url":"https://github.com/libexpat/libexpat/pull/1393","tags":[]},{"url":"https://www.vulncheck.com/advisories/libexpat-heap-buffer-over-read-in-xmlparse-c-via-xml-parsebuffer","tags":[]}],"exploitRefs":[{"url":"https://github.com/libexpat/libexpat/commit/13c5f63a7f1c52c2feee3b16a1134d4fb68e9ea0","tags":[]},{"url":"https://github.com/libexpat/libexpat/pull/1393","tags":[]}],"hasPoc":true,"ai":{"summary":"libexpat contains a heap buffer over-read vulnerability that allows attackers to read adjacent heap memory, potentially exposing pointers and function addresses that can defeat ASLR and enable further exploitation. This occurs when XML_ParseBuffer advances the parse buffer end without validating against allocated buffer size, leading to out-of-bounds reads.","exploitability":"Exploitation requires a caller-supplied buffer with repeated XML_ParseBuffer calls, making it moderately difficult but possible, especially in applications that process XML data with dynamic buffers.","blast_radius":"The vulnerability could affect any application using libexpat before commit 13c5f63 for XML parsing, potentially leading to information disclosure and ASLR bypass that could enable more sophisticated attacks across multiple systems.","remediation":"Upgrade to libexpat version including commit 13c5f63 or later.","detection":"No reliable host or network indicator is derivable from the published description.","tags":["memory-corruption","xml","information-disclosure"],"model":"garnet-coder","analyzedAt":"2026-10-15T08:58:22.101Z"}}