CVE-2026-40574: OAUTH2 Proxy Project OAUTH2 Proxy

Medium severity, CVSS 6.8. EPSS: 0.3% chance of exploitation in the next 30 days.

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.

Affected products

• OAUTH2 Proxy Project OAUTH2 Proxy: before 7.15.2 (fixed in 7.15.2)

Published 2026-04-21. Last modified 2026-06-17.