CVE-2026-9086 HIGH

CVE-2026-9086: Keycloak: keycloak: cross-site scripting (xss) via case-insensitive uri validation bypass

Vendor Red Hat
Product Red Hat build of Keycloak 26.4.13
Weakness CWE-79 · XSS
Published June 25, 2026
Last update June 30, 2026

CVSS base score

7.3/10
Attack vector Network
Attack complexity Low
Privileges required Low
User interaction Required
Confidentiality High
Integrity High

CVSS vector

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

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

June 25, 2026 CVE published
June 30, 2026 Record updated

Related vulnerabilities

04Related CVE