CVE-2025-4091

Name	CVE-2025-4091
Description	Memory safety bugs present in Firefox 137, Thunderbird 137, Firefox ESR 128.9, and Thunderbird 128.9. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 138, Firefox ESR < 128.10, Thunderbird < 138, and Thunderbird < 128.10.
Source	CVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
References	DLA-4167-1, DLA-4172-1, DSA-5910-1, DSA-5912-1

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
firefox (PTS)	sid	138.0.4-1	fixed
firefox-esr (PTS)	bullseye	115.14.0esr-1~deb11u1	vulnerable
	bullseye (security)	128.10.1esr-1~deb11u1	fixed
	bookworm	128.10.0esr-1~deb12u1	fixed
	bookworm (security)	128.10.1esr-1~deb12u1	fixed
	sid, trixie	128.10.1esr-1	fixed
thunderbird (PTS)	bullseye	1:115.12.0-1~deb11u1	vulnerable
	bullseye (security)	1:128.10.1esr-1~deb11u1	fixed
	bookworm	1:128.10.0esr-1~deb12u1	fixed
	bookworm (security)	1:128.10.1esr-1~deb12u1	fixed
	trixie	1:128.10.0esr-1	fixed
	sid	1:128.10.1esr-1	fixed

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

Package	Type	Release	Fixed Version	Origin
firefox	source	(unstable)	138.0-1
firefox-esr	source	bullseye	128.10.1esr-1~deb11u1	DLA-4172-1
firefox-esr	source	bookworm	128.10.0esr-1~deb12u1	DSA-5910-1
firefox-esr	source	(unstable)	128.10.0esr-1
thunderbird	source	bullseye	1:128.10.1esr-1~deb11u1	DLA-4167-1
thunderbird	source	bookworm	1:128.10.0esr-1~deb12u1	DSA-5912-1
thunderbird	source	(unstable)	1:128.10.0esr-1

Notes

https://www.mozilla.org/en-US/security/advisories/mfsa2025-28/#CVE-2025-4091
https://www.mozilla.org/en-US/security/advisories/mfsa2025-29/#CVE-2025-4091
https://www.mozilla.org/en-US/security/advisories/mfsa2025-32/#CVE-2025-4091