CVE-2026-34457
CriticalCVSS 9.1Exploitation Probability (EPSS)
Low risk38th percentile - higher than 38% of all known CVEs
Summary
OAuth2 Proxy prior to version 7.15.2 contains an authentication bypass vulnerability in deployments using auth_request (e.g., nginx auth_request) with --ping-user-agent or --gcp-healthchecks enabled. The vulnerability allows access to protected upstream resources without authentication.
Risk Assessment
Unauthenticated attackers can bypass authentication and access protected upstream resources, leading to data disclosure.
Recommendation
Upgrade OAuth2 Proxy to version 7.15.2 or later. If upgrade is not possible, disable --ping-user-agent and --gcp-healthchecks.
Original NVD description (English source)
OAuth2 Proxy is a reverse proxy that provides authentication using OAuth2 providers. Versions prior to 7.15.2 contain a configuration-dependent authentication bypass in deployments where OAuth2 Proxy is used with an auth_request-style integration (such as nginx auth_request) and either --ping-user-agent is set or --gcp-healthchecks is enabled. In affected configurations, OAuth2 Proxy treats any request with the configured health check User-Agent value as a successful health check regardless of the requested path, allowing an unauthenticated remote attacker to bypass authentication and access protected upstream resources. Deployments that do not use auth_request-style subrequests or that do not enable --ping-user-agent/--gcp-healthchecks are not affected. This issue is fixed in 7.15.2.