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5.5 Medium

CVE-2026-107889 Keycloak-services: keycloak-services: stored xss on login page via kcsanitize bypass

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.

CVSS 3.1 detail

Vector CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:N

Exploitable remotely over the network, with an administrator account and without any user action; the impact on data or service is limited.

Attack vector
Network
Attack complexity
Low
Privileges required
High
Interaction
None
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

Affected products and versions

Product Affected versions Fixed in
Red Hat Build of Keycloak Versions not published
Red Hat Single Sign-On 7 Versions not published
Red Hat build of Keycloak 26.6.8 Versions not published
Red Hat build of Keycloak 26.6 26.6 earliest → < 26.6-24 26.6-24

Other CVEs of Red Hat Build of Keycloak

The 277 CVEs of Red Hat Build of Keycloak →
CVE-2026-120984 Keycloak-services: keycloak-services: manage-clients to arbitrary code execution through inline javascript policy import 9.1 Critical CVE-2026-9797 Keycloak: keycloak: privilege escalation via client authentication manipulation by an authenticated administrator 6.5 Medium CVE-2026-97848 Keycloak-services: keycloak-services: protocol mapper with jsontype=json bypasses token sanitization 6.5 Medium CVE-2026-97367 Keycloak-services: keycloak-services: dcr azp and sid claim substitution allows account rest session takeover 6.4 Medium
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