CVE-2026-34454
Received Received - Intake
Session Fixation in OAuth2 Proxy 7.11.0–7.15.1 Causes Logout Bypass

Publication date: 2026-04-14

Last updated on: 2026-04-23

Assigner: GitHub, Inc.

Description
OAuth2 Proxy is a reverse proxy that provides authentication using OAuth2 providers. A regression introduced in 7.11.0 prevents OAuth2 Proxy from clearing the session cookie when rendering the sign-in page. In deployments that rely on the sign-in page as part of their logout flow, a user may be shown the sign-in page while the existing session cookie remains valid, meaning the browser session is not actually logged out. On shared workstations or devices, a subsequent user could continue to use the previous user's authenticated session. Deployments that use a dedicated logout/sign-out endpoint to terminate sessions are not affected. This issue is fixed in 7.15.2
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Meta Information
Published
2026-04-14
Last Modified
2026-04-23
Generated
2026-06-16
AI Q&A
2026-04-15
EPSS Evaluated
2026-06-15
NVD
CVE-2026-34454
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
oauth2_proxy_project oauth2_proxy From 7.11.0 (inc) to 7.15.2 (exc)
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-384 Authenticating a user, or otherwise establishing a new user session, without invalidating any existing session identifier gives an attacker the opportunity to steal authenticated sessions.
CWE-613 According to WASC, "Insufficient Session Expiration is when a web site permits an attacker to reuse old session credentials or session IDs for authorization."
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Executive Summary

This vulnerability is a regression introduced in OAuth2 Proxy version 7.11.0 that prevents the application from clearing the session cookie when rendering the sign-in page.

As a result, in deployments that rely on the sign-in page as part of their logout process, the user may see the sign-in page but the session cookie remains valid, meaning the browser session is not truly logged out.

On shared devices, this can allow a subsequent user to continue using the previous user's authenticated session.

Deployments that use a dedicated logout or sign-out endpoint to terminate sessions are not affected by this issue.

The issue is fixed in version 7.15.2.

Impact Analysis

This vulnerability can impact you by allowing unauthorized access to an authenticated session on shared workstations or devices.

If the logout flow relies on the sign-in page rather than a dedicated logout endpoint, the session cookie remains valid even after the user appears to have logged out.

This means a subsequent user of the same device could continue to use the previous user's session, potentially accessing sensitive information or performing actions as that user.

This could lead to confidentiality and integrity issues.

Mitigation Strategies

To mitigate this vulnerability, upgrade OAuth2 Proxy to version 7.15.2 or later, where the issue is fixed.

Alternatively, if your deployment uses a dedicated logout or sign-out endpoint to terminate sessions, you are not affected by this issue.

Compliance Impact

This vulnerability allows a user session cookie to remain valid even after the sign-in page is rendered, potentially enabling subsequent users on shared devices to access the previous user's authenticated session.

Such behavior could lead to unauthorized access to user data, which may conflict with compliance requirements in standards like GDPR and HIPAA that mandate proper session termination and protection of personal or sensitive information.

However, the CVE description does not explicitly mention compliance impacts or regulatory considerations.

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