CVE-2025-3523

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.
UI
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTNIST
6.4 MEDIUM
NETWORK
HIGH
NONE
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:H/A:L
mozillaCNA
---
---
CISA-ADPADP
6.4 MEDIUM
NETWORK
HIGH
NONE
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:H/A:L
Awaiting analysis
This vulnerability is currently awaiting analysis.
Base Score
CVSS 3.x
EPSS Score
Percentile: 17%
Debian logo
Debian Releases
Debian Product
Codename
thunderbird
bullseye
vulnerable
bullseye (security)
1:128.11.0esr-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
1:128.11.0esr-1
fixed
Ubuntu logo
Ubuntu Releases
Ubuntu Product
Codename
thunderbird
plucky
not-affected
oracular
not-affected
noble
not-affected
jammy
needs-triage
focal
needs-triage
Common Weakness Enumeration
Vulnerability Media Exposure
References
https://bugzilla.mozilla.org/show_bug.cgi?id=1958385
https://www.mozilla.org/security/advisories/mfsa2025-26/
https://www.mozilla.org/security/advisories/mfsa2025-27/