cve.bz

CVE-2026-76835

9.3 criticalEPSS 0.5%

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.

CVSS 4.0
9.3CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
CVSS 3.1
9.1CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
EPSS
0.5% chance of exploitation in the next 30 days; higher than 39% of CVEs (scores of 2026-10-25)
CWE
CWE-290
Published
Modified
Record from
the NVD, synced

Packages (OSV)

AdvisoryEcosystemPackageAffectedFixed in
GHSA-7x63-xv5r-3p2xGogithub.com/oauth2-proxy/oauth2-proxy/v7>=7.5.0 <7.15.27.15.2
GO-2026-5236Gogithub.com/oauth2-proxy/oauth2-proxyall versionsno fix published
GO-2026-5236Gogithub.com/oauth2-proxy/oauth2-proxy/v7>=7.5.0 <7.15.27.15.2

References

Check your stackJSON