CVE-2026-76641

Name	CVE-2026-76641
Description	Expat through 2.8.3 contains an out-of-bounds read vulnerability that allows attackers to trigger memory corruption by processing XML with external entity parsers created via XML_ExternalEntityParserCreate. A struct size mismatch between ELEMENT_TYPE members causes storeAtts to read the attIndex member past allocated memory boundaries, resulting in failure to normalize whitespace in non-CDATA attributes or a wild pointer dereference causing a segfault. This vulnerability was introduced by the fix for CVE-2026-66046.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
expat (PTS)	bullseye	2.2.10-2+deb11u5	fixed
	bullseye (security)	2.2.10-2+deb11u7	fixed
	bookworm	2.5.0-1+deb12u2	fixed
	bookworm (security)	2.5.0-1+deb12u1	fixed
	trixie	2.7.1-2	fixed
	trixie (security)	2.8.3-1~deb13u1	fixed
	forky, sid	2.8.3-1	fixed

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
expat	source	(unstable)	(not affected)

Notes

- expat <not-affected> (Vulnerable code not present)
https://github.com/libexpat/libexpat/pull/1331
Introduced with: https://github.com/libexpat/libexpat/commit/f8f7c4ffd883e3c2c58f0ebb49416a6c1d248738
Fixed by: https://github.com/libexpat/libexpat/commit/98599f6dcc2b460410881fe420f5f55d6bec63bf
Vulnerability covered by this CVE is introduced by the fix for CVE-2026-66046.