CVE-2025-0239mediumCWE-295

CVE-2025-0239: medium-severity vulnerability in Mozilla Firefox

Alt-Svc ALPN validation failure when redirected

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13Vexday Risk Score

No sign of exploitation. No public exploitation artifact known so far.

ssvc Trackcvss 4epss 0.2%
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 · FirefoxMozilla · Thunderbird
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