OAuth2 Proxy: Health Check User-Agent Matching Bypasses Authentication in auth_request Mode
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Security bypass
- Confidentiality · integrity · availability
- High · High · None
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-290.
Summary
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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| oauth2-proxy | oauth2-proxy | before 7.15.2 | 7.15.2 | Patch available | CNA |
| — | github.com/oauth2-proxy/oauth2-proxy/v7 (Go) | before 7.15.2 | 7.15.2 | Patch available | GHSA-5hvv-m4w4-gf6v |
| — | github.com/oauth2-proxy/oauth2-proxy (Go) | up to 3.2.0 | — | No fix listed | GHSA-5hvv-m4w4-gf6v |
- oauth2-proxy Vendoroauth2-proxy Affected before 7.15.2 Fixed in 7.15.2 Patch available CNA
- github.com/oauth2-proxy/oauth2-proxy/v7 (Go) Vendor— Affected before 7.15.2 Fixed in 7.15.2 Patch available GHSA-5hvv-m4w4-gf6v
- github.com/oauth2-proxy/oauth2-proxy (Go) Vendor— Affected up to 3.2.0 Fixed in — No fix listed GHSA-5hvv-m4w4-gf6v
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:oauth2_proxy_project:oauth2_proxy:*:*:*:*:*:*:*:* | before 7.15.2 | Vulnerable | oauth2-proxy |
- cpe:2.3:a:oauth2_proxy_project:oauth2_proxy:*:*:*:*:*:*:*:* Versions before 7.15.2 Vulnerable ·oauth2-proxy
Remediation
- Fix · CNA oauth2-proxy (oauth2-proxy) Fixed in 7.15.2
- Fix · GHSA-5hvv-m4w4-gf6v github.com/oauth2-proxy/oauth2-proxy/v7 (Go) Fixed in 7.15.2 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2026-34457
- 2026-10-03 Alias added: GHSA-5hvv-m4w4-gf6v
- 2026-10-13 EPSS moved to the 50th–90th percentile
- 2026-10-25 EPSS moved to the below the 50th percentile
References
More oauth2-proxy Oauth2 Proxy vulnerabilities
- TI-2025-34353 OAuth2-Proxy has authentication bypass in oauth2-proxy skip_auth_routes due to Query Parameter inclusion CVSS 3.1CRITICAL 9.1
- TI-2026-29315 OAuth2 Proxy has an Authentication Bypass via X-Forwarded-Uri Header Spoofing CVSS 3.1CRITICAL 9.1
- TI-2026-29698 OAuth2 Proxy has an Authentication Bypass via Fragment Confusion in skip_auth_routes and skip_auth_regex CVSS 3.1HIGH 8.2
- TI-2017-14408 CSRF in Bitly oauth2_proxy 2.1 during authentication flow CVSS 3.0HIGH 8.8
- TI-2020-08927 Open Redirect in OAuth2 Proxy CVSS 3.1HIGH 7.1
- TI-2026-29314 OAuth2 Proxy has an Authorization Bypass in Email Domain Validation via Malformed Multi-@ Email Claims CVSS 3.1MEDIUM 6.8
Sources
- CVE-2026-34457 · CVE Program
- CVE-2026-34457 · NVD
- FIRST EPSS
- GHSA-5hvv-m4w4-gf6v · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences