CVE-2026-86143

Name	CVE-2026-86143
Description	In xmlIO in libxml2 before 2.15.4, an inconsistency in xmlOutputWriteCallback and xmlBufUse causes negative lengths to reach write callbacks, aka a lack of a check for integer overflow before calling writecallback. This has security relevance for many types of uses of that length value within a callback.
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)
Debian Bugs	1146744

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
libxml2 (PTS)	bookworm	2.9.14+dfsg-1.3~deb12u6	vulnerable
	bookworm (security)	2.9.14+dfsg-1.3~deb12u4	vulnerable
	trixie	2.12.7+dfsg+really2.9.14-2.1+deb13u3	vulnerable
	trixie (security)	2.12.7+dfsg+really2.9.14-2.1+deb13u1	vulnerable
	forky, sid	2.15.4+dfsg-1	fixed

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

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
libxml2	source	(unstable)	2.15.4+dfsg-1			1146744

Notes

https://gitlab.gnome.org/GNOME/libxml2/-/work_items/1111
Fixed by: https://gitlab.gnome.org/GNOME/libxml2/-/commit/90f293ba74d28b1d570920382e707586f68ebf35 (v2.15.4)