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OpenAdvisories
Critical · 9.1 CVE-2026-34457 BIT-oauth2-proxy-2026-34457EUVD-2026-22761GHSA-5hvv-m4w4-gf6vGO-2026-5147

OAuth2 Proxy: Health Check User-Agent Matching Bypasses Authentication in auth_request Mode

Published Apr 14, 2026 · Updated Apr 15, 2026 · Assigned by GitHub_M

Description

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.

Affected products

VendorProductAffectedFixed
oauth2-proxy oauth2-proxy < 7.15.2 —

Fixed in Linux distributions

Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.

ReleasePackageFixed inAdvisory
openSUSE Leap 16.0 govulncheck-vulndb 0.0.20260723T184607-160000.1.1 openSUSE-SU-2026:21483-1

Affected packages

Advisories 1

References