CVE-2025-0239EPSS p12.2%

CVE-2025-0239CVE-2025-0239

mozilla / firefox

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.

Scoring

CVSS 4.0 ()
VectorCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
EPSS0.23% probability of exploitation · percentile 12.2% · 2026-10-05T12:00:23Z
Last modified2026-10-05
Sourced from NVD + FIRST.org EPSS. Curated for EU compliance use cases by Adam Lundqvist, Founder at SQUR.