CVE-2026-40574 Details
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.
An authorization bypass vulnerability has been identified in OAuth2 Proxy versions prior to 7.15.2. This issue arises within the email domain enforcement feature, allowing an attacker to authenticate using a malformed email claim that appears to satisfy domain checks. The vulnerability specifically impacts deployments that rely on email domain restrictions and accept email claims from identity providers or claim mappings that do not strictly validate email formats. The issue is most relevant in self-hosted or custom OpenID Connect environments, as well as federated setups where unexpected claim values can be introduced to OAuth2 Proxy. Standard hosted providers that enforce proper email formatting are not affected.
Users are advised to upgrade to OAuth2 Proxy version 7.15.2 or later. In addition, ensure that the configured identity provider does not send malformed or attacker-controlled email claim values.
Metrics
CVSS 4.0 Severity and Vector Strings:
No CVSS 4.0 data is available for this CVE.
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
CISA-ADP
Assessed Apr 21, 2026References to Advisories, Solutions, and Tools
By selecting these links, you will be leaving this site. These are references gathered from the official CVE record and are not endorsed by Volerion.
| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/oauth2-proxy/oauth2-proxy/security/advisories/GHSA-c5c4-8r6x-56w3 | [email protected] | Vendor Advisory |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-863 | Incorrect Authorization | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| oauth2 proxy project oauth2 proxy | < 7.15.2 |
CPE
Remediation
| |
Change History
4 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jun 17, 2026 | CVE Modified | [email protected] |
| Jun 17, 2026 | CVE Modified | CISA-ADP |
| Apr 27, 2026 | Initial Analysis | [email protected] |
| Apr 21, 2026 | New CVE Received | [email protected] |