{"schemaVersion":3,"id":"CVE-2026-40575","aliases":["RHSA-2026:58471","GHSA-7x63-xv5r-3p2x","BIT-oauth2-proxy-2026-40575","BIT-oauth2-proxy-2026-76835","CVE-2026-76835","GO-2026-5236"],"status":"published","duplicateOf":null,"title":null,"description":"OAuth2 Proxy honours a client-supplied X-Forwarded-Uri header when deciding whether a request may skip authentication, because the guard added for CVE-2026-40575 is inert in the default reverse-proxy configuration. GetRequestURI in pkg/requests/util/util.go prefers that header over the real request URI whenever CanTrustForwardedHeaders returns true, and isAllowedPath in oauthproxy.go matches the skip_auth_routes and skip_auth_regex allow list against the resulting path. CanTrustForwardedHeaders in pkg/apis/middleware/scope.go grants that trust when the caller's address is in the trusted proxy set, and buildTrustedProxyNetSet falls back to defaultTrustedProxyIPs, which is 0.0.0.0/0 and ::/0, whenever reverse proxy mode is enabled without trusted_proxy_ip configured. Every client is therefore treated as a trusted proxy. An unauthenticated attacker can request a protected upstream path while setting X-Forwarded-Uri to a value matching an allow-listed route, so the skip-auth decision is made against the spoofed value while the upstream receives the protected path unchanged.","dates":{"published":"2026-04-21T23:20:30.486Z","modified":"2026-07-15T01:00:45.240Z","reserved":null,"kevAdded":[],"kevDue":[]},"cvss":{"headline":{"score":9.3,"severity":"critical","version":"4.0","versionLabel":"v4.0","source":"NVD","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","computed":false,"selection":"backend-summary"},"metrics":[{"version":"3.1","versionLabel":"v3.1","source":"CVE.org","score":9.1,"severity":"critical","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","exploitability":null,"impact":null,"computed":false},{"version":"3.1","versionLabel":"v3.1","source":"OSV · Red 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