CVE-2025-12390: Session Fixation (CVSS 6)

Description

A flaw was found in Keycloak. In Keycloak where a user can accidentally get access to another user's session if both use the same device and browser. This happens because Keycloak sometimes reuses session identifiers and doesn’t clean up properly during logout when browser cookies are missing. As a result, one user may receive tokens that belong to another user.

Is your site exposed to CVE-2025-12390?

Run a free security scan — no signup, results in seconds.

CVSS v3.1 Score

6.0

MEDIUM

CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:N

Weakness Type (CWE)

CWE-384 CWE-384

References

Other References

https://access.redhat.com/errata/RHSA-2025:21370 https://access.redhat.com/errata/RHSA-2025:21371 https://access.redhat.com/errata/RHSA-2025:22088 https://access.redhat.com/errata/RHSA-2025:22089 https://access.redhat.com/security/cve/CVE-2025-12390 https://bugzilla.redhat.com/show_bug.cgi?id=2406793 https://github.com/keycloak/keycloak/issues/43853

Frequently Asked Questions

What is CVE-2025-12390? +

A flaw was found in Keycloak. In Keycloak where a user can accidentally get access to another user's session if both use the same device and browser. This happens because Keycloak sometimes reuses session identifiers and doesn’t clean up properly during logout when browser cookies are missing. As a result, one user may receive tokens that belong to another user. It has a CVSS v3.1 base score of 6.0 (MEDIUM).

How severe is CVE-2025-12390? +

CVE-2025-12390 has a CVSS v3.1 score of 6.0 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

How do I check if I'm vulnerable to CVE-2025-12390? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2025-0126

When configured using SAML, a session fixation vulnerability in the GlobalProtect™ login enables an attacker to impersonate a legitimate authorized …

CVE-2025-24502

An improper session validation allows an unauthenticated attacker to cause certain request notifications to be executed in the context of …

CVE-2025-24503

A malicious actor can fix the session of a PAM user by tricking the user to click on a specially …

CVE-2026-33384

QuickCMS allows a user's session identifier to be set before authentication. The value of this session ID stays the same …

CVE-2026-13707

Session fixation vulnerability in Wikimedia Foundation OAuth. This vulnerability is associated with program files src/Backend/MWOAuthServer.Php. This issue affects OAuth: from …

CVE-2025-42602

This vulnerability exists in Meon KYC solutions due to improper handling of access and refresh tokens in certain API endpoints …

CVE-2025-12390