← Back to the live CVE advisory feed

CVE-2026-76835: oauth2-proxy

Severity

9.3 (CRITICAL)

Vendor

OAUTH2-PROXY

Affected versions

7.15.2 through 7.15.4

Patch status

Unknown

Published

2026-08-24T18:17:21.570

Modified

2026-08-24T20:17:19.623

Why it matters

This matters because the issue affects identity or token handling. Successful exploitation could allow unauthorized authentication, client manipulation, or access to protected services.

Recommended admin actions

• Prioritize validation immediately due to critical CVSS severity.
• Treat internet-facing systems as higher priority.

Technical summary

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.

View the official NVD record for CVE-2026-76835

CVE data is sourced from NVD/CNA records and optional enrichment. Validate against the vendor advisory before taking production action.