CVE-2025-0239

Summary

CVE-2025-0239 is a vulnerability affecting Alt-Svc and ALPN (Application-Layer Protocol Negotiation) in Firefox versions below 134 and Firefox ESR below 128.6, as well as Thunderbird versions below 134 and Thunderbird below 128.6. The issue arises when these applications fail to properly validate certificates during redirection from a secure server to an insecure site, potentially exposing users to man-in-the-middle attacks. This vulnerability may result in compromised data or unauthorized access. Users are advised to update their browsers to the latest versions to mitigate this risk.

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