---
id: CVE-2026-9086
aliases:
  - GHSA-v3f7-2p4r-mwfw
title: >-
  Keycloak vulnerable to cross-site scripting (xss) via case-insensitive uri
  validation bypass
summary: >-
  Keycloak vulnerable to cross-site scripting (xss) via case-insensitive uri
  validation bypass
severity: high
cvss: 7.3
cwe:
  - CWE-79
vendor: keycloak
product: 'org.keycloak:keycloak-services'
ecosystem: maven
affected:
  - 'org.keycloak:keycloak-services < 26.6.4'
patched:
  - 'org.keycloak:keycloak-services 26.6.4'
published: '2026-10-29'
updated: '2026-10-29'
sourceUpdated: '2026-10-29T16:39:04Z'
source: GHSA
sourceUrl: 'https://github.com/advisories/GHSA-v3f7-2p4r-mwfw'
references:
  - url: >-
      https://github.com/keycloak/keycloak/security/advisories/GHSA-v3f7-2p4r-mwfw
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-9086'
  - url: 'https://access.redhat.com/errata/RHSA-2026:30049'
  - url: 'https://access.redhat.com/errata/RHSA-2026:30050'
  - url: 'https://access.redhat.com/errata/RHSA-2026:30083'
  - url: 'https://access.redhat.com/errata/RHSA-2026:30084'
  - url: 'https://access.redhat.com/security/cve/CVE-2026-9086'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2480170'
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-9086.json
  - url: 'https://github.com/advisories/GHSA-v3f7-2p4r-mwfw'
tags:
  - ghsa
  - maven
  - exploit-available
epss: 0.00781
epssPercentile: 0.55861
exploits:
  github: 1
  githubRepos:
    - 'https://github.com/Saku0512/CVE-2026-9086-poc'
  checkedAt: '2026-10-29T17:40:15.661Z'
exploitAvailable: true
ingestedAt: '2026-10-29T17:39:38.162Z'
---

## Overview

### 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.

## Affected packages

- `org.keycloak:keycloak-services < 26.6.4`

## Remediation

Upgrade to a patched release:

- `org.keycloak:keycloak-services 26.6.4`