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CVE-2026-40574

6.8 · MEDIUM

OAuth2 Proxy is a reverse proxy that provides authentication using OAuth2 providers.

Published Apr 21, 2026CWE-863EPSS 0.34%

Overview

CVE-2026-40574 is a medium-severity vulnerability. It was published on April 21, 2026 and has a CVSS 3.1 base score of 6.8 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 6.8, rated MEDIUM. It can be exploited remotely over the network. Some level of privileges is required for exploitation.

Technical description

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 [email protected]@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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/oauth2-proxy/oauth2-proxy/security/advisories/GHSA-c5c4-8r6x-56w3

How CyberStrike helps

Frequently asked questions

What is CVE-2026-40574?

CVE-2026-40574 is a medium-severity vulnerability. It was published on April 21, 2026 and has a CVSS 3.1 base score of 6.8 (MEDIUM).

How severe is CVE-2026-40574?

This vulnerability has a CVSS 3.1 base score of 6.8, rated MEDIUM. It can be exploited remotely over the network. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2026-40574?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-40574?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-40574 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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