CVE-2023-6544: Keycloak: authorization bypass

Severity: medium (CVSS 5.4 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-04-25 · updated 2026-06-17
Weakness: CWE-625

Description

A flaw was found in the Keycloak package. This issue occurs due to a permissive regular expression hardcoded for filtering which allows hosts to register a dynamic client. A malicious user with enough information about the environment could jeopardize an environment with this specific Dynamic Client Registration and TrustedDomain configuration previously unauthorized.

Affected products

Red Hat build of Keycloak 22: all versions — fixed in 22-13, 22-16, 22.0.10-1
Red Hat Single Sign-On 7.6 for RHEL 7: all versions — fixed in 0:18.0.13-1.redhat_00001.1.el7sso
Red Hat Single Sign-On 7.6 for RHEL 8: all versions — fixed in 0:18.0.13-1.redhat_00001.1.el8sso
Red Hat Single Sign-On 7.6 for RHEL 9: all versions — fixed in 0:18.0.13-1.redhat_00001.1.el9sso
Red Hat RHEL-8 based Middleware Containers: all versions — fixed in 7.6-46

How to fix

Upgrade to a fixed version: Red Hat build of Keycloak 22 22-13, 22-16, 22.0.10-1; Red Hat Single Sign-On 7.6 for RHEL 7 0:18.0.13-1.redhat_00001.1.el7sso; Red Hat Single Sign-On 7.6 for RHEL 8 0:18.0.13-1.redhat_00001.1.el8sso; Red Hat Single Sign-On 7.6 for RHEL 9 0:18.0.13-1.redhat_00001.1.el9sso; Red Hat RHEL-8 based Middleware Containers 7.6-46. Check the vendor advisory for mitigations.

References

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