CVE-2025-3523

Name	CVE-2025-3523
Description	When an email contains multiple attachments with external links via the X-Mozilla-External-Attachment-URL header, only the last link is shown when hovering over any attachment. Although the correct link is used on click, the misleading hover text could trick users into downloading content from untrusted sources. This vulnerability affects Thunderbird < 137.0.2 and Thunderbird < 128.9.2.
Source	CVE (at NVD; CERT, LWN, oss-sec, fulldisc, 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
thunderbird (PTS)	bullseye	1:115.12.0-1~deb11u1	vulnerable
	bullseye (security)	1:128.9.0esr-1~deb11u1	vulnerable
	bookworm	1:128.8.0esr-1~deb12u1	vulnerable
	bookworm (security)	1:128.9.0esr-1~deb12u1	vulnerable
	sid, trixie	1:128.9.0esr-1	vulnerable

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

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

Notes

[bookworm] - thunderbird <postponed> (Fix along with May security release)
https://www.mozilla.org/en-US/security/advisories/mfsa2025-27/#CVE-2025-3523