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Vulnerabilities

Vulnerability · CVE-2026-40575

OAuth2 Proxy is a reverse proxy that provides authentication using OAuth2 providers.

Published Apr 22, 2026 · catalog updated Jul 15, 2026 · oauth2 proxy project oauth2 proxy

Check if you run it

No confirmed exploitation is on record for CVE-2026-40575. EPSS is 0.73%. Act only if a listed version of oauth2 proxy project oauth2 proxy is installed.

Gaps on this record

  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Critical9.1
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.73%
Remediation
Advisory link
Affected products
cpe oauth2 proxy project/oauth2 proxy

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 header when is enabled and or 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 enabled and configure at least one or rule. This issue is patched in . Some workarounds are available for those who cannot upgrade immediately. Strip any client-provided header at the reverse proxy or load balancer level; explicitly overwrite 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 / rules where possible. For nginx-based deployments, ensure is set by nginx and not passed through from the client.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe oauth2 proxy project/oauth2 proxyversion unspecified

How to fix CVE-2026-40575

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-40575. EPSS is 0.73%. Act only if a listed version of oauth2 proxy project oauth2 proxy is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-290: Authentication Bypass by Spoofing. EPSS 0.73%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Nginx security

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Apr 22, 2026 · NIST NVD

    Detected

    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 header when is enabled and or 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 unauthenticate

  2. Jul 15, 2026 · NIST NVD

    Updated

    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 header when is enabled and or 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 unauthenticate

Sources

  • CVE.orgVulnerability recordCVE-2026-40575

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-40575

    30-day exploitation probability 0.7%

    first.org
  • NIST NVDVulnerability recordCVE-2026-40575

    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 header when is enabled and or is configured. An attacker can

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.