{"id":"CVE-2026-76835","revision":"a72a21a18d064c8a9b24f0f17ebe57c8","records":[{"revision":"a72a21a18d064c8a9b24f0f17ebe57c8","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-76835","aliases":[],"title":"OAuth2 Proxy 7.15.2 through 7.15.4 Authentication Bypass via X-Forwarded-Uri Under the Default Trusted Proxy Set","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.","state":0,"publishedAt":"2026-08-24T17:55:39.829+00:00","modifiedAt":"2026-10-08T15:25:05.218+00:00","affected":[{"ecosystem":"Vendor product","name":"oauth2-proxy","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"oauth2-proxy\",\n                    \"product\": \"oauth2-proxy\",\n                    \"defaultStatus\": \"unaffected\",\n                    \"versions\": [\n                        {\n                            \"version\": \"7.15.2\",\n                            \"lessThanOrEqual\": \"7.15.4\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"semver\"\n                        }\n                    ],\n                    \"repo\": \"https://github.com/oauth2-proxy/oauth2-proxy\",\n                    \"packageURL\": \"pkg:golang/github.com/oauth2-proxy/oauth2-proxy/v7\"\n                }"}],"metrics":[{"system":"CVSS 4.0","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","score":9.3,"severity":"CRITICAL"},{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","score":9.1,"severity":"CRITICAL"}],"references":["https://github.com/oauth2-proxy/oauth2-proxy","https://github.com/oauth2-proxy/oauth2-proxy/issues/3506","https://github.com/oauth2-proxy/oauth2-proxy/blob/v7.15.4/pkg/apis/middleware/scope.go","https://github.com/oauth2-proxy/oauth2-proxy/security/advisories/GHSA-7x63-xv5r-3p2x","https://www.vulncheck.com/advisories/oauth2-proxy-through-authentication-bypass-via-x-forwarded-uri-under-the-default-trusted-proxy-set"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-76835","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-76835","identifiers":["CVE-2026-76835"]},"retained":false,"historicalAffected":[]}],"coverage":[]}