A flaw was found in the login theme rendering component of Keycloak. The issue occurs because the security filter responsible for cleaning user input can be bypassed, allowing a realm administrator to store malicious scripts in display fields. This could result in unauthorized JavaScript execution in the browsers of users visiting the login page, potentially leading to data exposure or session interference.

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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

Fri, 09 Oct 2026 12:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

threat_severity

Moderate


Fri, 09 Oct 2026 05:00:00 +0000

Type Values Removed Values Added
Description A flaw was found in the login theme rendering component of Keycloak. The issue occurs because the security filter responsible for cleaning user input can be bypassed, allowing a realm administrator to store malicious scripts in display fields. This could result in unauthorized JavaScript execution in the browsers of users visiting the login page, potentially leading to data exposure or session interference.
Title Keycloak-services: keycloak-services: stored xss on login page via kcsanitize bypass
First Time appeared Redhat
Redhat build Keycloak
Redhat red Hat Single Sign On
Weaknesses CWE-79
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': 5.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:N'}


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cve-icon MITRE

Status: PUBLISHED

Assigner: redhat

Published:

Updated: 2026-10-09T04:28:55.081Z

Reserved: 2026-10-09T04:07:31.462Z

Link: CVE-2026-107889

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-10-09T05:16:44.583

Modified: 2026-10-09T16:37:45.710

Link: CVE-2026-107889

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-10-08T15:38:13Z

Links: CVE-2026-107889 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-10-09T06:30:17Z

Weaknesses