Vulnerability in Oauth2-Proxy
CVE-2026-34457
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.
EPSS exploit prediction
EPSS: 0.007 (50.5th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 50th percentile — 50.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.007 · change: +0.002
Affected products
- Oauth2-Proxy — versions < 7.15.2
- Oauth2 Proxy Project
Weakness classification (CWE)
References
- github.com/oauth2-proxy/oauth2-proxy/security/advisories/GHSA-5hvv-m4w4-gf6v (Mitigation, Vendor Advisory)
- github.com/oauth2-proxy/oauth2-proxy/releases/tag/v7.15.2 (Release Notes)
Frequently asked questions
- What is CVE-2026-34457?
- CVE-2026-34457 is a critical-severity vulnerability in Oauth2-Proxy, classified under Authentication Bypass by Spoofing. CVSS score: 9.1/10. Published 2026-04-14.
- How severe is CVE-2026-34457?
- Critical severity. CVSS v3 base score is 9.1 out of 10.