CVE-2026-40574: medium-severity vulnerability in oauth2-proxy
OAuth2 Proxy has an Authorization Bypass in Email Domain Validation via Malformed Multi-@ Email Claims
Published
E-mail alert when it lands in KEV, gets a public PoC or its score goes up.
13Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 6.8epss 0.2%
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.
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N
Affected products
oauth2-proxy · oauth2-proxyRelated CVEs — oauth2-proxy
In the same product, most dangerous first.
CVE-2021-21291MEDIUMSubdomain checking of whitelisted domains could allow unintended redirectsEPSS 1.6%CVE-2025-54576CRITICALOAuth2-Proxy has authentication bypass in oauth2-proxy skip_auth_routes due to Query Parameter inclusionEPSS 1.2%CVE-2021-21411MEDIUMIncorrect authorization in OAuth2-ProxyEPSS 1.1%CVE-2025-64484HIGHOAuth2-Proxy vulnerable to header smuggling via underscore, leading to potential privilege escalationEPSS 0.7%CVE-2026-40575CRITICALOAuth2 Proxy has an Authentication Bypass via X-Forwarded-Uri Header SpoofingEPSS 0.5%CVE-2026-34457CRITICALOAuth2 Proxy: Health Check User-Agent Matching Bypasses Authentication in auth_request ModeEPSS 0.5%