Vulnerability · CVE-2026-40575
OAuth2 Proxy is a reverse proxy that provides authentication using OAuth2 providers.
Published Apr 22, 2026 · corrected/updated Jul 15, 2026 · oauth2 proxy project oauth2 proxy · evidence confidence high
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.
Grounded briefings
Catalog interpretations for three audiences. Each brief cites ingested metadata and the original advisories below. They are not independent research and they do not invent exploit steps.
Executive
CVE-2026-40575 is a critical public vulnerability record for oauth2 proxy project oauth2 proxy. It is not currently listed in the CISA Known Exploited catalog. Check the linked vendor or CERT advisories for patch status. This summary is a catalog interpretation of the ingested metadata and cites the original advisories below.
System administrator
Identify whether oauth2 proxy project oauth2 proxy is in your estate, then compare installed versions with the affected ranges. Affected packages or ranges on record: oauth2 proxy project/oauth2 proxy. Check the linked vendor or CERT advisories for patch status. Prefer the vendor or distribution advisory linked in Sources before changing production systems. This is a catalog interpretation, not a runbook.
Security analyst
Signals on file: CVSS 9.1, EPSS 0.7%. It is not currently listed in the CISA Known Exploited catalog. Weakness classes: CWE-290. Sources contributing to this record: cve_org, epss, nvd. Public exploit references, when present, are outbound links only and are not proof of active exploitation. This is a catalog interpretation of stored metadata.
Exploitation and remediation
Exploitation evidence
Not listed as known exploited in CISA KEV. Not in CISA KEV or VulnCheck KEV.
Patch and remediation
No required-action text is stored yet. Use the vendor or CERT links in Sources for patch availability.
Safe detection guidance
Compare installed versions with the affected ranges below and verify the advisory from the original publisher. This site stores metadata and outbound links only; it does not ship exploit code or proof-of-concept payloads.
Technology hubs
Code
The project this record applies to. Exploit listings stay in References.
Timeline
Detection, updates, and resolution for this record.
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
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
Affected
- cpe oauth2 proxy project/oauth2 proxyversion unspecified
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