CVE-2026-4636 Keycloak: keycloak: uma policy bypass allows authenticated users to gain unauthorized access to victim-owned resources.
Authenticated users with uma_protection role can bypass UMA policy validation to access victim-owned resources and obtain sensitive information.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-4636?
CVE-2026-4636 is a high-severity missing authorization vulnerability in Redhat Build of Keycloak, published on 2 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
A flaw was found in Keycloak. An authenticated user with the uma_protection role can bypass User-Managed Access (UMA) policy validation. This allows the attacker to include resource identifiers owned by other users in a policy creation request, even if the URL path specifies an attacker-owned resource. Consequently, the attacker gains unauthorized permissions to victim-owned resources, enabling them to obtain a Requesting Party Token (RPT) and access sensitive information or perform unauthorized actions.
Weakness: CWE-551
Which versions are affected by CVE-2026-4636?
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 | 26.5.7 |
org.keycloak:keycloak-services Maven | All versions | 26.5.7 |
keycloak Bitnami | From 26.2.0 | 26.2.1, 26.3.0, 26.4.1, 26.5.0 |
Products include Redhat Build of Keycloak.
How do I fix CVE-2026-4636?
Upgrade org.keycloak:keycloak-services to 26.5.7 or later.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-4636 being exploited?
There is no known exploitation of CVE-2026-4636 in the wild and no public exploit code.
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-2026-4636, ECHO-5dd9-eb24-e2ed, GHSA-f2hx-5fx3-hmcv, MINI-v8cr-2688-jhwf, MINI-vx69-qh8r-425r.