CVE-2026-77214 (GCVE-0-2026-77214)

Vulnerability from cvelistv5 – Published: 2026-10-07 14:35 – Updated: 2026-10-07 14:35 X_Open Source
VLAI
Title
libexpat Heap Buffer Over-read in xmlparse.c via XML_ParseBuffer
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 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.
Severity
8.3 (High)
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
8.2 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:L
CWE
Assigner
References
Impacted products
Vendor Product Version CPE status
libexpat libexpat Affected: 0 , ≤ 2.8.5 (semver)
Unaffected: 13c5f63a7f1c52c2feee3b16a1134d4fb68e9ea0 (git)
guessed Create a notification for this product.
Date Public
2026-09-24 00:00
Credits
Fabian Wahle (Hap Security) Filippo Tedeschi VulnCheck
Show details on NVD website
To clipboard 

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}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



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