CVE-2026-40574: OAuth2 Proxy has an Authorization Bypass in Email Domain Validation via Malformed Multi-@ Email Claims
CVE-2026-40574 · Severity: medium · CVSS 6.8 · Published 2026-04-21
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.
Yes. github.com/oauth2-proxy/oauth2-proxy/v7 (Go): upgrade to 7.15.2 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
Am I affected by CVE-2026-40574?
Check whether you run github.com/oauth2-proxy/oauth2-proxy (Go), github.com/oauth2-proxy/oauth2-proxy/v7 (Go) or Oauth2 Proxy Project Oauth2 Proxy at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
How to fix
github.com/oauth2-proxy/oauth2-proxy/v7 (Go): upgrade to 7.15.2 or later
go get github.com/oauth2-proxy/oauth2-proxy/v7@v7.15.2