{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-40575", "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "state": "PUBLISHED", "assignerShortName": "GitHub_M", "dateReserved": "2026-04-14T13:24:29.475Z", "datePublished": "2026-04-21T23:20:30.486Z", "dateUpdated": "2026-04-22T14:15:41.802Z"}, "containers": {"cna": {"title": "OAuth2 Proxy has an Authentication Bypass via X-Forwarded-Uri Header Spoofing", "problemTypes": [{"descriptions": [{"cweId": "CWE-290", "lang": "en", "description": "CWE-290: Authentication Bypass by Spoofing", "type": "CWE"}]}], "metrics": [{"cvssV3_1": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 9.1, "baseSeverity": "CRITICAL", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N", "version": "3.1"}}], "references": [{"name": "https://github.com/oauth2-proxy/oauth2-proxy/security/advisories/GHSA-7x63-xv5r-3p2x", "tags": ["x_refsource_CONFIRM"], "url": "https://github.com/oauth2-proxy/oauth2-proxy/security/advisories/GHSA-7x63-xv5r-3p2x"}], "affected": [{"vendor": "oauth2-proxy", "product": "oauth2-proxy", "versions": [{"version": ">= 7.5.0, < 7.15.2", "status": "affected"}]}], "providerMetadata": {"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "shortName": "GitHub_M", "dateUpdated": "2026-04-21T23:20:30.486Z"}, "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."}], "source": {"advisory": "GHSA-7x63-xv5r-3p2x", "discovery": "UNKNOWN"}}, "adp": [{"metrics": [{"other": {"type": "ssvc", "content": {"timestamp": "2026-04-22T14:15:18.160877Z", "id": "CVE-2026-40575", "options": [{"Exploitation": "none"}, {"Automatable": "yes"}, {"Technical Impact": "total"}], "role": "CISA Coordinator", "version": "2.0.3"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-04-22T14:15:41.802Z"}}]}}

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{"configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:oauth2_proxy_project:oauth2_proxy:*:*:*:*:*:*:*:*", "matchCriteriaId": "03587628-7B66-41FF-B89D-DF35A5134CD7", "versionEndExcluding": "7.15.2", "versionStartIncluding": "7.5.0", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "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."}], "id": "CVE-2026-40575", "lastModified": "2026-04-27T19:29:10.667", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 9.1, "baseSeverity": "CRITICAL", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 5.2, "source": "security-advisories@github.com", "type": "Secondary"}]}, "published": "2026-04-22T00:16:27.817", "references": [{"source": "security-advisories@github.com", "tags": ["Vendor Advisory"], "url": "https://github.com/oauth2-proxy/oauth2-proxy/security/advisories/GHSA-7x63-xv5r-3p2x"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-290"}], "source": "security-advisories@github.com", "type": "Primary"}]}

{"bugzilla": {"description": "oauth2-proxy: github.com/oauth2-proxy/oauth2-proxy: OAuth2 Proxy: Authentication bypass due to spoofed X-Forwarded-Uri header", "id": "2460449", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2460449"}, "csaw": false, "cvss3": {"cvss3_base_score": "8.7", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N", "status": "draft"}, "cwe": "CWE-290", "details": ["A flaw was found in OAuth2 Proxy. When configured with `--reverse-proxy` and either `--skip-auth-regex` or `--skip-auth-route`, the proxy may trust a client-supplied `X-Forwarded-Uri` header. An unauthenticated remote attacker can exploit this by spoofing the header, leading to an authentication bypass. This allows unauthorized access to protected routes without a valid session."], "mitigation": {"lang": "en:us", "value": "This issue can be mitigated by one of the options bellow:\n1) Strip any client-provided `X-Forwarded-Uri` header at any layer before it reaches `oauth2-proxy`;\n2) Overwrite the `X-Forwarded-Uri` header with the actual request URI before the request reaches `oauth2-proxy`. If you are using NGINX you can use the following example to create your tailored mitigation:\n~~~\nlocation /internal-auth/ {\ninternal; # Ensure external users can't access this path\n# Make sure the OAuth2 Proxy knows where the original request came from.\nproxy_set_header Host $host;\nproxy_set_header X-Real-IP $remote_addr;\n# set the value to the actual $request_uri and therefore strip any user provided X-Forwarded-Uri\nproxy_set_header X-Forwarded-Uri $request_uri;\nproxy_pass http://oauth2-proxy:4180/;\n}\n~~~\n3) Restrict direct client access to OAuth2 Proxy so it can only be reached through a trusted reverse proxy;\n4) Remove or narrow --skip-auth-route / --skip-auth-regex rules where possible;"}, "name": "CVE-2026-40575", "package_state": [{"cpe": "cpe:/a:redhat:ceph_storage:9", "fix_state": "Affected", "package_name": "rhceph/oauth2-proxy-rhel9", "product_name": "Red Hat Ceph Storage 9"}], "public_date": "2026-04-21T23:20:30Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-40575\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-40575\nhttps://github.com/oauth2-proxy/oauth2-proxy/security/advisories/GHSA-7x63-xv5r-3p2x"], "statement": "There's an Important flaw in `oauth2-proxy` software where it trusts a client supplied `X-Forwarded-Uri` request header. This header is used by `oauth2-proxy` to identify the original URI from the incoming request it's currently handling. An attacker which manages to spoof the requests sent to it when it's running behind a reverse-proxy may change this header field to match the routes or the regular expressions configured to have authentication skipped, as a consequence the attacker may manage to have access to protected resources or internal routes without any kind of authentication being required resulting in a high impact for data confidentiality and integrity for the services positioned behind the reverse proxy.\nRed Hat Product Security team has rated this vulnerability as having a impact of Important as for a `oauth2-proxy` being considered vulnerable it should be being executed with the following specific configuration options enabled:\n1) `--reverse-proxy`\n2) `--skip-auth-regex` or `--skip-auth-route`\nAdditionally to exploit this vulnerability the attacker should be able to change the headers in the request being sent (either via a local proxy or by performing a Man-In-The-Middle attack before) and should have previous knowledge about the routes or patterns of URI which the authentication are being skipped by the `oauth2-proxy` deployment.", "threat_severity": "Important"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[7.5.0,7.15.2)"}}], "enrichment": {"confidence": 86.0, "confidence_source": "matching", "scores": [{"score": 86.0, "source": "matching"}]}, "original": {"product": "oauth2-proxy", "source": "cna", "vendor": "oauth2-proxy"}, "product": "oauth2_proxy", "vendor": "oauth2_proxy_project"}], "analysis": {"en": {"generated_at": "2026-04-22T06:11:32.746745+00:00", "value": {"mitigation_remediation": ["Apply the available patch to upgrade to oauth2\u2011proxy v7.15.2 or later.", "Configure the reverse proxy or load balancer so that it does not forward client\u2011supplied X-Forwarded-Uri headers; instead, overwrite the header with the actual request URI before forwarding to OAuth2 Proxy.", "Remove or narrow any --skip-auth-regex or --skip-auth-route rules so that they match only the intended exempt paths.", "Restrict direct client access to the OAuth2 Proxy so that it is only reachable through a trusted reverse proxy in the infrastructure."], "summary": {"action": "Immediate Patch", "impact": "Authentication Bypass"}, "threat_synthesis": {"affected_systems": "Versions 7.5.0 through 7.15.1 of the oauth2\u2011proxy project that run with the --reverse-proxy flag and define at least one --skip-auth-regex or --skip-auth-route rule are affected. Deployments using these settings are at risk.", "description_and_impact": "OAuth2 Proxy may accept a client\u2011supplied X-Forwarded-Uri header when reverse proxy mode is enabled and skip\u2011auth rules are active. An attacker can spoof this header so OAuth2 Proxy evaluates authentication and skip\u2011auth logic against a different path than the one actually sent to the upstream application, resulting in an unauthenticated remote attacker bypassing authentication and accessing protected routes without a valid session.", "risk_and_exploitability": "The vulnerability carries a CVSS score of 9.1, indicating a high severity authentication bypass. No EPSS score is currently available, but the absence of a KEV listing does not reduce the risk; attackers who can reach the proxy instance can send crafted HTTP requests to manipulate the X-Forwarded-Uri header, escalating privilege and accessing restricted content. Exploitation requires only the ability to send requests to OAuth2 Proxy, which is common in web\u2011based deployments."}}}}, "created": "2026-04-22T02:15:05.403034+00:00", "updated": "2026-04-22T11:30:15.188871+00:00", "vendors": ["oauth2_proxy_project", "oauth2_proxy_project$PRODUCT$oauth2_proxy"]}