CVE-2026-93990

Name	CVE-2026-93990
Description	Expat through 2.8.4 fails to validate low surrogates following high surrogates in UTF-16 input, allowing malformed UTF-16 sequences to be accepted. Attackers can craft UTF-16 encoded XML with lone high surrogates that consume following code units, hiding markup characters from the parser and enabling XML injection attacks.
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)	bookworm	2.5.0-1+deb12u2	vulnerable
	bookworm (security)	2.5.0-1+deb12u3	vulnerable
	trixie (security), trixie	2.8.3-1~deb13u1	vulnerable
	forky, sid	2.8.4-1	vulnerable

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

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
expat	source	(unstable)	(unfixed)

Notes

https://github.com/libexpat/libexpat/pull/1282
Fixed by: https://github.com/libexpat/libexpat/commit/0cfd15bdf4b2c22d6b0df73610709dfb60921091
Fixed by: https://github.com/libexpat/libexpat/commit/28fcfba540f6933aa8904a1514c4811713d2ab72