CVE-2026-77214
8.2, highlibexpat Out-of-Bounds Read Vulnerability
- CVSS
- 8.2, high high CVSS v3.1
- EPSS, next 30 days
- 0.5% higher than 44.7% of scored CVEs
- Exploitation
- No public evidence
- Published
- 7 Oct 202610 days ago
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.
Details
- Vendor
- Libexpat
- Product
- libexpat
- Weakness
- CWE-125 (opens in a new tab)
- Status
- Awaiting analysis
- Updated
- 7 Oct 2026
- Assigner
- disclosure@vulncheck.com
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:L
References 3
Patches and fixes 2
The kind is read from NVD's tags where present and from the shape of the URL otherwise, so treat it as a hint.
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Assembled from the NVD 2.0 API, the CISA Known Exploited Vulnerabilities Catalog and FIRST EPSS. Scores are as of our last collection on 17 Oct 2026, not the live upstream state.