CVE-2025-0239
Alt-Svc ALPN validation failure when redirected
CVSS Score
4.0
EPSS Score
0.0%
EPSS Percentile
0th
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.
| Vendor | mozilla |
| Product | firefox |
| Ecosystems | |
| Industries | Technology |
| Published | Jan 7, 2025 |
| Last Updated | Apr 13, 2026 |
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Affected Versions
Mozilla / Firefox
All versions affected Mozilla / Thunderbird
All versions affected References
bugzilla.mozilla.org: https://bugzilla.mozilla.org/show_bug.cgi?id=1929156 mozilla.org: https://www.mozilla.org/security/advisories/mfsa2025-01/ mozilla.org: https://www.mozilla.org/security/advisories/mfsa2025-02/ mozilla.org: https://www.mozilla.org/security/advisories/mfsa2025-04/ mozilla.org: https://www.mozilla.org/security/advisories/mfsa2025-05/ lists.debian.org: https://lists.debian.org/debian-lts-announce/2025/01/msg00004.html
Credits
Paul Gerste