Heap Buffer Over-Read Vulnerability in Expat Library by Expat Project

CVE-2026-77214

What is CVE-2026-77214?

The libexpat library prior to a specific commit contains a vulnerability in the xmlparse.c file that allows for a heap buffer over-read. The issue arises when the XML_ParseBuffer function is called, which improperly advances its parsing buffer end based on an unvalidated user-supplied length. This oversight allows m_bufferEnd to exceed the bounds of the allocated buffer, leading to potential disclosure of sensitive information from adjacent heap memory, such as pointers to heap structures and function pointers. This can pose serious security risks, as it may facilitate further exploitation by revealing critical internal application structures.

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