---
id: CVE-2026-16103
title: A flaw was found in the keycloak-services component of Keycloak
summary: >-
  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
  handl…
severity: medium
cvss: 4.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N'
cwe:
  - CWE-305
  - CWE-841
vendor: redhat
product: build_of_keycloak
affected:
  - build_of_keycloak
published: '2026-07-17'
updated: '2026-08-31'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-16103'
references:
  - url: 'https://access.redhat.com/security/cve/CVE-2026-16103'
    label: secalert@redhat.com
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2501736'
    label: secalert@redhat.com
tags:
  - nvd
epss: 0.00345
epssPercentile: 0.27973
ingestedAt: '2026-08-31T13:08:32.482Z'
---

## Overview

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.

## Affected

- `build_of_keycloak`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.