CVE-2026-9086 Keycloak: keycloak: cross-site scripting (xss) via case-insensitive uri validation bypass
Administrators can bypass URI validation to inject XSS payloads, enabling arbitrary code execution in the Keycloak origin when victims interact with crafted links.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-9086?
CVE-2026-9086 is a high-severity cross-site scripting vulnerability in Redhat Build of Keycloak, published on 25 Jun 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
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.
Weakness: CWE-79
Which versions are affected by CVE-2026-9086?
3 open source packages ship an affected version, including org.keycloak:keycloak-services and keycloak. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
org.keycloak:keycloak-services Maven | All versions | 26.6.4 |
org.keycloak:keycloak-services Maven | All versions | 26.6.4 |
keycloak Bitnami | From 26.4.0 | 26.4.13, 26.6.4 |
Products include Redhat Build of Keycloak.
How do I fix CVE-2026-9086?
Upgrade org.keycloak:keycloak-services to 26.6.4 or later.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-9086 being exploited?
There is no known exploitation of CVE-2026-9086 in the wild and no public exploit code.
Public exploit code: 1 proofs of concept on GitHub.
Other vulnerabilities in Redhat Build of Keycloak
- CVE-2026-15572 Keycloak-services: keycloak-services: dcr protocol mapper type-swap policy bypass allows privilege escalation
- CVE-2026-3047 Keycloak SAML Broken has Authentication Bypass by Primary Weakness
- CVE-2026-15573 Keycloak-services: keycloak-services: authorization bypass via unnormalized uri matching in pathmatcher
- CVE-2026-16102 Keycloak-services: keycloak-services: default dcr policy allows role forgery via user property mappers
- CVE-2026-1609 Org.keycloak/keycloak-quarkus-server: keycloak: unauthorized access via jwt authorization grant with disabled users
Sources
Also known as BIT-keycloak-2026-9086, GHSA-v3f7-2p4r-mwfw.