{"id":"CVE-2026-40575","sourceIdentifier":"security-advisories@github.com","published":"2026-04-22T00:16:27.817","lastModified":"2026-07-15T02:21:07.520","vulnStatus":"Modified","cveTags":[],"descriptions":[{"lang":"en","value":"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 `X-Forwarded-Uri` header when `--reverse-proxy` is enabled and `--skip-auth-regex` or `--skip-auth-route` 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 `--reverse-proxy` enabled and configure at least one `--skip-auth-regex` or `--skip-auth-route` rule. This issue is patched in `v7.15.2`. Some workarounds are available for those who cannot upgrade immediately. Strip any client-provided `X-Forwarded-Uri` header at the reverse proxy or load balancer level; explicitly overwrite `X-Forwarded-Uri` 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 `--skip-auth-regex` / `--skip-auth-route` rules where possible. For nginx-based deployments, ensure `X-Forwarded-Uri` is set by nginx and not passed through from the client."}],"affected":[{"source":"security-advisories@github.com","affectedData":[{"vendor":"oauth2-proxy","product":"oauth2-proxy","versions":[{"version":">= 7.5.0, < 7.15.2","status":"affected"}]}]},{"source":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c","affectedData":[{"vendor":"Red Hat","product":"Red Hat Ceph Storage 9","defaultStatus":"affected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","packageName":"rhceph/oauth2-proxy-rhel9","cpes":["cpe:/a:redhat:ceph_storage:9"]}]}],"metrics":{"cvssMetricV31":[{"source":"security-advisories@github.com","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","baseScore":9.1,"baseSeverity":"CRITICAL","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"NONE"},"exploitabilityScore":3.9,"impactScore":5.2},{"source":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N","baseScore":8.7,"baseSeverity":"HIGH","attackVector":"NETWORK","attackComplexity":"HIGH","privilegesRequired":"NONE","userInteraction":"NONE","scope":"CHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"NONE"},"exploitabilityScore":2.2,"impactScore":5.8}],"ssvcV203":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","ssvcData":{"timestamp":"2026-04-22T14:15:18.160877Z","id":"CVE-2026-40575","options":[{"exploitation":"none"},{"automatable":"yes"},{"technicalImpact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}]},"weaknesses":[{"source":"security-advisories@github.com","type":"Secondary","description":[{"lang":"en","value":"CWE-290"}]},{"source":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c","type":"Secondary","description":[{"lang":"en","value":"CWE-290"}]}],"configurations":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:a:oauth2_proxy_project:oauth2_proxy:*:*:*:*:*:*:*:*","versionStartIncluding":"7.5.0","versionEndExcluding":"7.15.2","matchCriteriaId":"03587628-7B66-41FF-B89D-DF35A5134CD7"}]}]}],"references":[{"url":"https://github.com/oauth2-proxy/oauth2-proxy/security/advisories/GHSA-7x63-xv5r-3p2x","source":"security-advisories@github.com","tags":["Vendor Advisory"]},{"url":"https://access.redhat.com/security/cve/CVE-2026-40575","source":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2460449","source":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-40575.json","source":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"}]}