What’s Vulnerable › Vulnerabilities

CVE-2025-12390: Org.keycloak.protocol.oidc.endpoints.logoutendpoint: offline session takeover due to reused authentication session id

• Severity: medium (CVSS 6.0 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-10-28 · updated 2026-10-18
• Weakness: CWE-384

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.

Affected products

• Red Hat build of Keycloak 26.4: all versions — fixed in 26.2-12, 26.2.11-1, 26.4-3, 26.4.4-1
• Keycloak: before 26.0.0 — fixed in 26.0.0

How to fix

Upgrade to a fixed version: Red Hat build of Keycloak 26.4 26.2-12, 26.2.11-1, 26.4-3, 26.4.4-1; Keycloak 26.0.0. Check the vendor advisory for mitigations.

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

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