CVE-2025-0239

Alt-Svc ALPN validation failure when redirected

CVSS 4 MEDIUMEPSS 0.2%CWE-295

Vexday Risk Score

13Low

SSVC decision (CISA)

Track

No exploitation signal → monitor

CVSS 4EPSS 0.2%KEV nãoPoC —Nuclei —Metasploit —Patch —

Lifecycle

07 Jan 2025Published on NVD

Recommendation: Monitor — no exploitation signal at the moment.

When using Alt-Svc, ALPN did not properly validate certificates when the original server is redirecting to an insecure site. This vulnerability was fixed in Firefox 134, Firefox ESR 128.6, Thunderbird 134, and Thunderbird 128.6.

CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Affected products

Mozilla · Firefox Mozilla · Thunderbird

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References

https://bugzilla.mozilla.org/show_bug.cgi?id=1929156 https://lists.debian.org/debian-lts-announce/2025/01/msg00004.html 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/