CVE-2026-11800 Org.keycloak:keycloak-services: keycloak: authentication bypass via jwt algorithm confusion
Attackers with valid client credentials can bypass JWT signature verification to impersonate federated users and escalate privileges in Keycloak.
- 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-2026-11800?
CVE-2026-11800 is a high-severity authentication bypass vulnerability in Redhat Build of Keycloak, published on 25 Jun 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. This JWT algorithm confusion vulnerability in the JWT Authorization Grant flow allows an attacker with valid client credentials to bypass signature verification. By forging an assertion, the attacker can create unauthorized access tokens. This enables the attacker to impersonate any federated user linked to the affected Identity Provider, leading to unauthorized access and potential privilege escalation.
Weakness: CWE-347
Which versions are affected by CVE-2026-11800?
1 open source package ship an affected version, including keycloak. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
keycloak Bitnami | From 26.6.0 | 26.6.4 |
Products include Redhat Build of Keycloak.
How do I fix CVE-2026-11800?
Upgrade keycloak to 26.6.4 or later.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-11800 being exploited?
There is no known exploitation of CVE-2026-11800 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-2026-11800, GHSA-gqj5-2xp5-3qmp.