Improper Validation of Consistency within Input in Keycloak - CVE-2026-18209
Published: July 31, 2026 / Updated: September 5, 2026
Vulnerability identifier: #VU146976
CSH Severity: Low
CVSS v4: 2.1 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-18209
CWE-ID: CWE-1288
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to influence session handling or cause account confusion.
The vulnerability exists due to improper validation of consistency within input in the keycloak-services component when processing redirect URLs with wildcard redirect URIs. A remote attacker can inject duplicate security parameters into a login response to influence session handling or cause account confusion.
User interaction is required, and exploitation depends on a client application trusting injected data instead of security information from Keycloak.
Affected software
Keycloak
How to mitigate CVE-2026-18209
Install security update from vendor's website.
Keycloak - update to 26.7.3