redhat build-keycloak CVE-2026-107889 vulnerability in Red Hat Products
Published on October 9, 2026

Keycloak-services: keycloak-services: stored xss on login page via kcsanitize bypass
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.

Vendor Advisory Vendor Advisory NVD

Vulnerability Analysis

CVE-2026-107889 can be exploited with network access, and requires user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have a small impact on confidentiality and integrity, and no impact on availability.

Exploitation:
NONE
Automatable:
NO
Technical Impact:
PARTIAL
Attack Vector:
NETWORK
Attack Complexity:
LOW
Privileges Required:
HIGH
User Interaction:
NONE
Scope:
CHANGED
Confidentiality Impact:
LOW
Integrity Impact:
LOW
Availability Impact:
NONE

Timeline

Reported to Red Hat.

Made public.

Weakness Type

What is a XSS Vulnerability?

The software does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.

CVE-2026-107889 has been classified to as a XSS vulnerability or weakness.


Products Associated with CVE-2026-107889

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Red Hat Build Keycloak
Red Hat Single Sign On

Affected Versions

Red Hat build of Keycloak 26.6: Red Hat build of Keycloak 26.6: Red Hat build of Keycloak 26.6: Red Hat build of Keycloak 26.6.8: Red Hat build of Keycloak 26.6.8: Red Hat Single Sign-On 7: