CVE-2025-3523

EUVD-2025-10966
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
NISTPrimary
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
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
Base Score
CVSS 3.x
EPSS Score
Percentile: 47%
Affected Products (NVD)
VendorProductVersion
mozillathunderbird
𝑥
< 128.9.2
mozillathunderbird
129.0 ≤
𝑥
< 137.0.2
𝑥
= Vulnerable software versions
Debian logo
Debian Releases
Debian Product
Codename
thunderbird
bookworm
1:140.6.0esr-1~deb12u1
fixed
bookworm (security)
1:140.8.0esr-1~deb12u1
fixed
bullseye
vulnerable
bullseye (security)
1:140.8.0esr-1~deb11u1
fixed
forky
1:140.8.0esr-1
fixed
sid
1:140.8.0esr-1
fixed
trixie
1:140.6.0esr-1~deb13u1
fixed
trixie (security)
1:140.8.0esr-1~deb13u1
fixed
Ubuntu logo
Ubuntu Releases
Ubuntu Product
Codename
thunderbird
focal
dne
jammy
Fixed 1:128.12.0+build1-0ubuntu0.22.04.1
released
noble
not-affected
oracular
not-affected
plucky
not-affected
Common Weakness Enumeration
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/