OAuth2 Proxy has an Authentication Bypass via X-Forwarded-Uri Header Spoofing

Summary

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.

Timeline

1. Apr 21, 2026, 11:20 PM UTCCVE published
2. Apr 22, 2026, 2:15 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: yes · Technical impact: total

3. Jul 15, 2026, 1:00 AM UTCRecord last updated

Affected versions

• oauth2-proxy oauth2-proxy

  From 7.5.0 · fixed in 7.15.2

• github.com/oauth2-proxy/oauth2-proxy/v7Go

  From 7.5.0 · fixed in 7.15.2

• github.com/oauth2-proxy/oauth2-proxyGo

  All versions

References 1