A flaw was found in the Client-Initiated Backchannel Authentication (CIBA) implementation of Keycloak. The CIBA endpoint fails to properly validate the sub parameter, allowing it to be stored as an additional request parameter. During the token issuance process, this injected value overwrites the legitimate subject identifier. This allows an attacker to authenticate as themselves but receive security tokens belonging to a different victim user, leading to unauthorized account access.
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Fixes

Solution

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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.

History

Thu, 05 Nov 2026 17:30:00 +0000

Type Values Removed Values Added
Description A flaw was found in the Client-Initiated Backchannel Authentication (CIBA) implementation of Keycloak. The CIBA endpoint fails to properly validate the sub parameter, allowing it to be stored as an additional request parameter. During the token issuance process, this injected value overwrites the legitimate subject identifier. This allows an attacker to authenticate as themselves but receive security tokens belonging to a different victim user, leading to unauthorized account access.
Title Keycloak-services: keycloak-services: ciba sub parameter injection causes attacker authentication to issue victim tokens
First Time appeared Redhat
Redhat build Keycloak
Redhat red Hat Single Sign On
Weaknesses CWE-20
CPEs cpe:/a:redhat:build_keycloak:
cpe:/a:redhat:red_hat_single_sign_on:7
Vendors & Products Redhat
Redhat build Keycloak
Redhat red Hat Single Sign On
References
Metrics cvssV3_1

{'score': 6.8, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: redhat

Published:

Updated: 2026-11-05T17:15:54.587Z

Reserved: 2026-09-24T05:29:37.511Z

Link: CVE-2026-97174

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-11-05T18:17:11.493

Modified: 2026-11-05T18:17:11.630

Link: CVE-2026-97174

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-11-05T19:00:20Z

Weaknesses