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CVE-2026-16103— Keycloak-services: keycloak-services: incomplete fix for ciba brute-force lockout bypass at token redemption

Quick assessment

Affected
Red Hat Red Hat Build of Keycloak
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Keycloak是Keycloak组织开源的一种身份和访问管理解决方案。 keycloak存在安全漏洞，该漏洞源于keycloak-services组件中对CVE-2026-9798的修复不完整，暴力破解保护检查添加到了客户端发起反向信道认证（CIBA）初始化处理程序但未包含在令牌赎回处理程序中，允许具有有效客户端凭据的攻击者获取已因暴力破解保护锁定的用户账户的访问令牌和刷新令牌。

CVSS 4.3 · Medium EPSS 0.34% · P28

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 6

VendorProduct Version RangeStatus
Red Hat Red Hat Build of Keycloak any affected
any affected
any affected
Red Hat Red Hat Data Grid 8 any unaffected
Red Hat Red Hat JBoss Enterprise Application Platform Expansion Pack any unaffected
Red Hat Red Hat Single Sign-On 7 any unaffected
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I. Basic Information for CVE-2026-16103

Vulnerability Information
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Vulnerability Title
Keycloak-services: keycloak-services: incomplete fix for ciba brute-force lockout bypass at token redemption
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
使用基本弱点进行的认证绕过
Source: CVE Program / CVE List V5
Vulnerability Title
Keycloak 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Keycloak是Keycloak组织开源的一种身份和访问管理解决方案。 keycloak存在安全漏洞，该漏洞源于keycloak-services组件中对CVE-2026-9798的修复不完整，暴力破解保护检查添加到了客户端发起反向信道认证（CIBA）初始化处理程序但未包含在令牌赎回处理程序中，允许具有有效客户端凭据的攻击者获取已因暴力破解保护锁定的用户账户的访问令牌和刷新令牌。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Red Hat Red Hat Build of Keycloak - cpe:/a:redhat:build_keycloak:
Red Hat Red Hat Build of Keycloak - cpe:/a:redhat:build_keycloak:
Red Hat Red Hat Build of Keycloak - cpe:/a:redhat:build_keycloak:
Red Hat Red Hat Data Grid 8 - cpe:/a:redhat:jboss_data_grid:8
Red Hat Red Hat JBoss Enterprise Application Platform Expansion Pack - cpe:/a:redhat:jbosseapxp
Red Hat Red Hat Single Sign-On 7 - cpe:/a:redhat:red_hat_single_sign_on:7

II. Public POCs for CVE-2026-16103

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III. Intelligence Information for CVE-2026-16103

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Vendor Advisories for CVE-2026-16103 (2)

Same Patch Batch · Red Hat · 2026-07-17 · 8 CVEs total

CVE-2026-15943 5.5 MEDIUM Keycloak-services: keycloak-services: oidc idp update reuses masked client secret after to
CVE-2026-16093 5.4 MEDIUM Keycloak-services: keycloak-services: required signed-jwt assertion policy can be bypassed
CVE-2026-16089 5.4 MEDIUM Keycloak-services: keycloak-services: authorization codes can be retargeted to another cli
CVE-2026-16106 4.9 MEDIUM Keycloak-services: keycloak-services: incorrect authorization in admin role-composite dele
CVE-2026-16072 4.9 MEDIUM Keycloak-services: keycloak-services: organization invitation link exposure allows unautho
CVE-2026-16104 4.3 MEDIUM Keycloak-services: keycloak-services: authenticator config endpoint exposes raw recaptcha
CVE-2026-16108 4.3 MEDIUM Keycloak-services: keycloak-services: realm default-group reads disclose hidden groups und

IV. Related Vulnerabilities

Same product: Red Hat Build of Keycloak
Same vendor: Red Hat
Same weakness: CWE-305