Mailu - Mailu - CRITICAL - CVE-2026-85751. A vulnerability exists in Mailu's mail server affecting deployments with PROXY_AUTH_WHITELIST configured, but the REAL_IP_HEADER unset. This configuration allows unauthenticated attackers to exploit client-controlled X-Forwarded-By headers, spoofing trusted proxy identities and bypassing authentication mechanisms. The issue is resolved in Mailu versions 2024.06.55 and helm-charts 2.7.3, ensuring secure handling of proxy authentication.