A flaw was found in Keycloak, an open-source identity and access management solution. When a user account is temporarily locked due to repeated failed login attempts, an attacker with valid client credentials can exploit the Client-Initiated Backchannel Authentication (CIBA) flow to bypass this brute-force protection. This allows continued authentication attempts and token issuance even when the account should be locked, potentially enabling further unauthorized access attempts.

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Advisories

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Fixes

Solution

No solution given by the vendor.


Workaround

To mitigate this issue, ensure that Client-Initiated Backchannel Authentication (CIBA) is not enabled in Keycloak realms unless explicitly required. If CIBA is enabled, consider disabling it to prevent the bypass of brute-force protection mechanisms. Consult Keycloak documentation for instructions on managing CIBA configuration.

History

Thu, 28 May 2026 08:45:00 +0000

Type Values Removed Values Added
First Time appeared Redhat build Of Keycloak
Vendors & Products Redhat build Of Keycloak

Thu, 28 May 2026 06:00:00 +0000

Type Values Removed Values Added
Description A flaw was found in Keycloak, an open-source identity and access management solution. When a user account is temporarily locked due to repeated failed login attempts, an attacker with valid client credentials can exploit the Client-Initiated Backchannel Authentication (CIBA) flow to bypass this brute-force protection. This allows continued authentication attempts and token issuance even when the account should be locked, potentially enabling further unauthorized access attempts.
Title Keycloak: keycloak: brute-force protection bypass in ciba flow
First Time appeared Redhat
Redhat build Keycloak
Weaknesses CWE-305
CPEs cpe:/a:redhat:build_keycloak:
Vendors & Products Redhat
Redhat build Keycloak
References
Metrics cvssV3_1

{'score': 4.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: redhat

Published:

Updated: 2026-05-28T04:37:09.472Z

Reserved: 2026-05-28T03:51:03.615Z

Link: CVE-2026-9798

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-05-28T06:16:29.330

Modified: 2026-05-28T06:16:29.330

Link: CVE-2026-9798

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-05-28T08:30:11Z

Weaknesses