{"id":"CVE-2026-40575","revision":"80787ef47d81472d9b5efa2e712fc1fa","records":[{"revision":"80787ef47d81472d9b5efa2e712fc1fa","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-40575","aliases":[],"title":"OAuth2 Proxy has an Authentication Bypass via X-Forwarded-Uri Header Spoofing","description":"OAuth2 Proxy is a reverse proxy that provides authentication using OAuth2 providers. Versions 7.5.0 through 7.15.1 may trust a client-supplied `X-Forwarded-Uri` header when `--reverse-proxy` is enabled and `--skip-auth-regex` or `--skip-auth-route` is configured. An attacker can spoof this header so OAuth2 Proxy evaluates authentication and skip-auth rules against a different path than the one actually sent to the upstream application. This can result in an unauthenticated remote attacker bypassing authentication and accessing protected routes without a valid session. Impacted users are deployments that run oauth2-proxy with `--reverse-proxy` enabled and configure at least one `--skip-auth-regex` or `--skip-auth-route` rule. This issue is patched in `v7.15.2`. Some workarounds are available for those who cannot upgrade immediately. Strip any client-provided `X-Forwarded-Uri` header at the reverse proxy or load balancer level; explicitly overwrite `X-Forwarded-Uri` with the actual request URI before forwarding requests to OAuth2 Proxy; restrict direct client access to OAuth2 Proxy so it can only be reached through a trusted reverse proxy; and/or remove or narrow `--skip-auth-regex` / `--skip-auth-route` rules where possible. For nginx-based deployments, ensure `X-Forwarded-Uri` is set by nginx and not passed through from the client.","state":0,"publishedAt":"2026-04-21T23:20:30.486+00:00","modifiedAt":"2026-07-15T01:00:45.24+00:00","affected":[{"ecosystem":"Vendor product","name":"oauth2-proxy","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"oauth2-proxy\",\n                    \"product\": \"oauth2-proxy\",\n                    \"versions\": [\n                        {\n                            \"version\": \">= 7.5.0, < 7.15.2\",\n                            \"status\": \"affected\"\n                        }\n                    ]\n                }"}],"metrics":[{"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/security/advisories/GHSA-7x63-xv5r-3p2x"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-40575","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-40575","identifiers":["CVE-2026-40575"]},"retained":false,"historicalAffected":[]}],"coverage":[]}