CVE-2026-76835 OAuth2 Proxy 7.15.2 through 7.15.4 Authentication Bypass via X-Forwarded-Uri Under the Default Trusted Proxy Set
Unauthenticated attackers can bypass authentication by spoofing the X-Forwarded-Uri header in default reverse-proxy configurations, accessing protected resources.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-76835?
CVE-2026-76835 is a critical authentication bypass vulnerability in oauth2-proxy, published on 24 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-290
Which versions are affected by CVE-2026-76835?
How do I fix CVE-2026-76835?
Upgrade to a fixed version.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-76835 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-76835 exists.
Sources
Also known as GHSA-vvqv-7vrf-88vh.