Attacker can re-enable and take over disabled clients via Registration Access Token

Summary

A flaw was found in Keycloak's client registration service. A remote attacker, possessing a previously issued Registration Access Token (RAT), could exploit this vulnerability to re-enable a client that an administrator had explicitly disabled. This bypasses security controls, allowing the attacker to reset the client's secret and potentially regain privileged API access. The primary impact includes unauthorized information disclosure and potential integrity compromise. A flaw was found in Keycloak's client registration service. A remote attacker, possessing a previously issued Registration Access Token (RAT), could exploit this vulnerability to re-enable a client that an administrator had explicitly disabled. This bypasses security controls, allowing the attacker to reset the client's secret and potentially regain privileged API access. The primary impact includes unauthorized information disclosure and potential integrity compromise. A Moderate flaw was found in Keycloak where a disabled client can be re-enabled by an attacker who retains a Registration Access Token (RAT) from a prior legitimate client registration. This allows the attacker to bypass the administrator's explicit intent to disable the client, reset its secret, and restore OAuth client_credentials capability, potentially leading to unauthorized access to resources. Red Hat severity: Moderate — CVSS 6.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N). Weakness: CWE-613. Fixed by RHSA-2026:30050, RHSA-2026:30049, RHSA-2026:30084, RHSA-2026:30083 — update the affected packages (`sudo dnf update`). Affected Red Hat products: Red Hat build of Keycloak 26.4; Red Hat build of Keycloak 26.4.13; Red Hat build of Keycloak 26.6; Red Hat build of Keycloak 26.6.4.