Vulnerability Description
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 Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Mozilla | Firefox | < 128.6.0 |
| Mozilla | Thunderbird | < 128.6.0 |
Related Weaknesses (CWE)
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=1929156Issue TrackingPermissions Required
- https://www.mozilla.org/security/advisories/mfsa2025-01/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2025-02/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2025-04/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2025-05/Vendor Advisory
- https://lists.debian.org/debian-lts-announce/2025/01/msg00004.html
FAQ
What is CVE-2025-0239?
CVE-2025-0239 is a vulnerability with a CVSS score of 4.0 (MEDIUM). 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...
How severe is CVE-2025-0239?
CVE-2025-0239 has been rated MEDIUM with a CVSS base score of 4.0/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2025-0239?
Check the references section above for vendor advisories and patch information. Affected products include: Mozilla Firefox, Mozilla Thunderbird.