CyberRota Analysis
AI-GeneratedOAuth2 Proxy is vulnerable due to its improper handling of the X-Forwarded-Uri header, allowing unauthenticated attackers to bypass authentication for protected routes by spoofing this header. The default configuration inadvertently trusts all clients as proxies, enabling attackers to exploit this flaw and access sensitive resources without proper authentication. Organizations using OAuth2 Proxy should prioritize addressing this vulnerability, particularly those with reverse proxy configurations, to prevent unauthorized access to their systems.
Public Exploit Signal
A public exploit, PoC, GitHub repository or Metasploit reference was detected for this CVE.
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Original NVD 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.