{"id":"CVE-2026-40574","summary":"OAuth2 Proxy has an Authorization Bypass in Email Domain Validation via Malformed Multi-@ Email Claims","details":"OAuth2 Proxy is a reverse proxy that provides authentication using OAuth2 providers. Prior to 7.15.2, an authorization bypass exists in OAuth2 Proxy as part of the email_domain enforcement option. An attacker may be able to authenticate with an email claim such as attacker@evil.com@company.com and satisfy an allowed domain check for company.com, even though the claim is not a valid email address. The issue ONLY affects deployments that rely on email_domain restrictions and accept email claim values from identity providers or claim mappings that do not strictly enforce normal email syntax. This vulnerability is fixed in 7.15.2.","aliases":["BIT-oauth2-proxy-2026-40574","GHSA-c5c4-8r6x-56w3","GO-2026-5314"],"modified":"2026-07-08T08:13:12.507963975Z","published":"2026-04-21T16:32:34.537Z","database_specific":{"cna_assigner":"GitHub_M","cwe_ids":["CWE-863"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/40xxx/CVE-2026-40574.json"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/40xxx/CVE-2026-40574.json"},{"type":"ADVISORY","url":"https://github.com/oauth2-proxy/oauth2-proxy/security/advisories/GHSA-c5c4-8r6x-56w3"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-40574"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/oauth2-proxy/oauth2-proxy","events":[{"introduced":"0"},{"fixed":"5961fd99b42c3625b8ef08690d38be5cb37f44b0"}],"database_specific":{"cpe":"cpe:2.3:a:oauth2_proxy_project:oauth2_proxy:*:*:*:*:*:*:*:*","source":["AFFECTED_FIELD","CPE_RANGE"],"extracted_events":[{"introduced":"0"},{"fixed":"7.15.2"}]}}],"versions":["v7.15.1","v7.15.0","v7.14.3","v7.14.2","v7.14.1","v7.14.0","v7.13.0","v7.12.0","v7.11.0","v7.10.0","v7.9.0","v7.8.2","v7.8.1","v7.8.0","v7.7.1","v7.7.0","v7.6.0","v7.5.1","v7.5.0","v7.4.0","v7.3.0","v7.2.1","v7.2.0","v7.1.3","v7.1.2","v7.1.1","v7.1.0","v7.0.1","v7.0.0","v6.1.1","v6.1.0","v6.0.0","v5.1.0","v5.0.0","v4.1.0","v4.0.0","v3.2.0","v3.1.0","v3.0.0","v2.2","v2.1","v2.0.1","v2.0","v1.1.1","v1.1","v1.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-40574.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N"}]}