CVE-2025-0239

When using Alt-Svc, ALPN did not properly validate certificates when the original server is redirecting to an insecure site. This vulnerability affects Firefox < 134, Firefox ESR < 128.6, Thunderbird < 134, and Thunderbird < 128.6.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTNIST
4 MEDIUM
LOCAL
LOW
NONE
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
mozillaCNA
---
---
CISA-ADPADP
4 MEDIUM
LOCAL
LOW
NONE
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Base Score
CVSS 3.x
EPSS Score
Percentile: 5%
VendorProductVersion
mozillafirefox
𝑥
< 128.6.0
mozillafirefox
𝑥
< 134.0
mozillathunderbird
𝑥
< 128.6.0
mozillathunderbird
129.0 ≤
𝑥
< 134.0
𝑥
= Vulnerable software versions
Debian logo
Debian Releases
Debian Product
Codename
firefox
sid
139.0-1
fixed
firefox-esr
bullseye
vulnerable
bullseye (security)
128.11.0esr-1~deb11u1
fixed
bookworm
128.10.0esr-1~deb12u1
fixed
bookworm (security)
128.11.0esr-1~deb12u1
fixed
trixie
128.10.1esr-1
fixed
sid
128.11.0esr-1
fixed
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
Common Weakness Enumeration
References
https://bugzilla.mozilla.org/show_bug.cgi?id=1929156
https://www.mozilla.org/security/advisories/mfsa2025-01/
https://www.mozilla.org/security/advisories/mfsa2025-02/
https://www.mozilla.org/security/advisories/mfsa2025-04/
https://www.mozilla.org/security/advisories/mfsa2025-05/