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 was fixed in Firefox 134, Firefox ESR 128.6, Thunderbird 134, and Thunderbird 128.6.

Score

CVSS 3.1 4.0 Medium

Status

Modified - security@mozilla.org

Published

2025-01-07

Last modified

2026-10-05

Weaknesses

CWE-295

Affected products

• Firefox (Mozilla)
• Thunderbird (Mozilla)

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/
• https://lists.debian.org/debian-lts-announce/2025/01/msg00004.html