Session Fixation in Keycloak - CVE-2026-16089
Published: July 17, 2026 / Updated: September 5, 2026
Vulnerability identifier: #VU146969
CSH Severity: Low
CVSS v4: 5.8 [CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:A/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-16089
CWE-ID: CWE-384
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote user to obtain access tokens for a victim\'s identity.
The vulnerability exists due to improper binding of OAuth 2.0 authorization codes to clients in the keycloak-services component when redeeming an intercepted authorization code. A remote user can modify the intercepted code to redeem it using their own client to obtain access tokens for a victim\'s identity.
User interaction is required.
Affected software
Keycloak
How to mitigate CVE-2026-16089
Install security update from vendor's website.
Keycloak - update to 26.7.3