Improper Validation of Consistency within Input in Red Hat build of Keycloak - CVE-2026-9689
Published: September 11, 2026
Vulnerability identifier: #VU148991
CSH Severity: Low
CVSS v4: 1.8 [CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-9689
CWE-ID: CWE-1288
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause a client application to process attacker-controlled OIDC response parameters.
The vulnerability exists due to HTTP parameter pollution in OIDC redirect URI processing when processing a crafted authorization URL. A remote attacker can craft an authorization URL with duplicate response parameters to cause a client application to process attacker-controlled OIDC response parameters.
Exploitation requires a broad redirect URI configuration, a client application that uses first-wins handling for duplicate query parameters, and user interaction to open the crafted URL.
Affected software
Red Hat build of Keycloak
How to mitigate CVE-2026-9689
Install security update from vendor's website.
Red Hat build of Keycloak - update to 26.6.5