CVE-2026-16103

Keycloak-services: keycloak-services: incomplete fix for ciba brute-force lockout bypass at token redemption

Published Jul 17, 2026 CVSS 3.1 · 4.3 Medium EPSS < 1% KEV · Not listed
Description
A flaw was found in the keycloak-services component of Keycloak. This issue is an incomplete fix for CVE-2026-9798, where brute-force protection checks were added to the Client-Initiated Backchannel Authentication (CIBA) initiation handler but were omitted from the token redemption handler. This allows an attacker with valid client credentials to obtain access and refresh tokens for a user account that has been locked due to brute-force protection, provided the authentication request was started before the lockout occurred and was approved by the user.

Remediation

Vendor Workaround

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
CPEs cpe:/a:redhat:build_keycloak: cpe:/a:redhat:build_keycloak:26.6::el9
References
Type Values Removed Values Added
Weaknesses CWE-305
Type Values Removed Values Added
First Time appeared Redhat build Of Keycloak
Redhat data Grid
Redhat jboss Enterprise Application Platform Expansion Pack
Vendors & Products Redhat build Of Keycloak
Redhat data Grid
Redhat jboss Enterprise Application Platform Expansion Pack
Type Values Removed Values Added
Weaknesses CWE-841
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description A flaw was found in the keycloak-services component of Keycloak. This issue is an incomplete fix for CVE-2026-9798, where brute-force protection checks were added to the Client-Initiated Backchannel Authentication (CIBA) initiation handler but were omitted from the token redemption handler. This allows an attacker with valid client credentials to obtain access and refresh tokens for a user account that has been locked due to brute-force protection, provided the authentication request was started before the lockout occurred and was approved by the user.
Title Keycloak-services: keycloak-services: incomplete fix for ciba brute-force lockout bypass at token redemption
First Time appeared Redhat
Redhat build Keycloak
Redhat jboss Data Grid
Redhat jbosseapxp
Redhat red Hat Single Sign On
CPEs cpe:/a:redhat:build_keycloak:
cpe:/a:redhat:jboss_data_grid:8
cpe:/a:redhat:jbosseapxp
cpe:/a:redhat:red_hat_single_sign_on:7
Vendors & Products Redhat
Redhat build Keycloak
Redhat jboss Data Grid
Redhat jbosseapxp
Redhat red Hat Single Sign On
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'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
redhat
Published
Updated
Nov 6, 2026, 5:34 PM
Reserved
Jul 17, 2026, 2:46 PM
Status
Modified
Published
Jul 17, 2026, 5:17 PM
Modified
Nov 6, 2026, 6:18 PM
Severity
Moderate
Public date
Jul 16, 2026, 4:53 PM