Incorrect Behavior Order: Authorization Before Parsing and Canonicalization in Keycloak - CVE-2026-4636
Published: September 10, 2026
Vulnerability identifier: #VU148937
CSH Severity: Medium
CVSS v4: 8.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-4636
CWE-ID: CWE-551
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote user to gain unauthorized permissions to victim-owned resources.
The vulnerability exists due to authorization before parsing and canonicalization in Keycloak User-Managed Access policy validation when creating a policy with resource identifiers owned by other users. A remote user can include victim-owned resource identifiers in a policy creation request for an attacker-owned resource to gain unauthorized permissions to victim-owned resources.
The user must have the uma_protection role. Successful exploitation can enable acquisition of a Requesting Party Token.
Affected software
Keycloak
Red Hat build of Keycloak
Red Hat build of Keycloak
How to mitigate CVE-2026-4636
Install security update from vendor's website.
Keycloak - update to 26.5.7
Red Hat build of Keycloak - addressed in versions 26.2.15, 26.4.11
Red Hat build of Keycloak - addressed in versions 26.2.15, 26.4.11