[ CVE-2026-9086 · Published 25 Jun 2026 ]
Keycloak vulnerable to cross-site scripting (xss) via case-insensitive uri validation bypass
CVSS 7.3
EPSS <1%Fix available
[ Description ]Official description
A flaw was found in Keycloak. A remote attacker with administrative privileges, specifically those with `manage-client` permission or access to client registration endpoints, could bypass client Uniform Resource Identifier (URI) validation. This is achieved by registering a malicious client with a specially crafted redirect URI using a case-insensitive `javascript:` or `data:` scheme. This Cross-Site Scripting (XSS) vulnerability allows for arbitrary code execution in the Keycloak origin when a victim clicks the crafted link, such as in the logout flow or the Admin Console.
[ Fixes ]Fixes and patches
- org.keycloak:keycloak-services 26.6.4Fixed version · GitHub Advisories · maven package org.keycloak:keycloak-services: upgrade to 26.6.4 or later (affected < 26.6.4)
[ Packages ]Affected open-source packages
- org.keycloak:keycloak-services mavenAffected < 26.6.4 · fixed in 26.6.4 · GHSA-v3f7-2p4r-mwfw
[ References ]References
- access.redhat.com/errata/RHSA-2026:30049vendor-advisoryx_refsource_REDHAT
- access.redhat.com/errata/RHSA-2026:30050vendor-advisoryx_refsource_REDHAT
- access.redhat.com/errata/RHSA-2026:30083vendor-advisoryx_refsource_REDHAT
- access.redhat.com/errata/RHSA-2026:30084vendor-advisoryx_refsource_REDHAT
- access.redhat.com/security/cve/CVE-2026-9086vdb-entryx_refsource_REDHAT
- bugzilla.redhat.com/show_bug.cgiissue-trackingx_refsource_REDHAT