Authentication Bypass Affecting oauth2-proxy-fips-advanced-compat package, versions <7.15.2-r0


Severity

Recommended
low

Based on default assessment until relevant scores are available.

Threat Intelligence

EPSS
0.73% (53rd percentile)

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  • Snyk IDSNYK-MINIMOSLATEST-OAUTH2PROXYFIPSADVANCEDCOMPAT-16093987
  • published17 Apr 2026
  • disclosed22 Apr 2026

Introduced: 17 Apr 2026

CVE-2026-40575  (opens in a new tab)
CWE-290  (opens in a new tab)

How to fix?

Upgrade Minimos:latest oauth2-proxy-fips-advanced-compat to version 7.15.2-r0 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream oauth2-proxy-fips-advanced-compat package and not the oauth2-proxy-fips-advanced-compat package as distributed by Minimos. See How to fix? for Minimos:latest relevant fixed versions and status.

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.

CVSS Base Scores

version 3.1