CVE-2025-12390: Red Hat build of Keycloak 26.2 · Session Fixation
Affects Red Hat build of Keycloak 26.2Source CVE Database V5
Not known to be exploited · CVSS 6.0 Medium.
Data as of 25 Oct 2026, 19:02 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 3% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:NExploitation evidence
Disclosed: evidence found.
CVE published 28 Oct 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-25.
What to do
AI-suggested
Organizations should immediately upgrade to a patched version of Red Hat Keycloak once available. In the interim, administrators should enforce strict session management policies, including ensuring that session identifiers are unique per login and properly invalidated on logout. Implementing browser cookie management policies to prevent cookie deletion or manipulation can reduce risk. Deploy endpoint security controls to restrict unauthorized local access and monitor for unusual session activity. Consider configuring Keycloak to enforce multi-factor authentication (MFA) to reduce the impact of session hijacking. Educate users about the risks of shared device usage and encourage logging out properly and avoiding shared browsers. Network segmentation and access controls can limit exposure of Keycloak instances to trusted users only. Regularly audit session logs for anomalies and integrate with SIEM solutions for real-time alerting on suspicious session behavior.
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.
References
- access.redhat.com/errata/RHSA-2025:21370 (opens in a new tab)
- access.redhat.com/errata/RHSA-2025:21371 (opens in a new tab)
- access.redhat.com/errata/RHSA-2025:22088 (opens in a new tab)
- access.redhat.com/errata/RHSA-2025:22089 (opens in a new tab)
- access.redhat.com/security/cve/CVE-2025-12390 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2406793 (opens in a new tab)