CVE-2026-11800
Org.keycloak:keycloak-services: keycloak: authentication bypass via jwt algorithm confusion
- State
- Published
- Severity
- 8.1 High
- Published
- Jun 25, 2026
- Updated
- Jul 15, 2026
- Reserved
- Jun 9, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 8.1 High | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N | redhat |
| 3.1 | 8.1 High | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N | redhat-SADP |
Weaknesses
- CWE-347 Improper Verification of Cryptographic Signature
Affected Products
| Product | Versions |
|---|---|
Red Hat build of Keycloak 26.6Red Hat |
|
Red Hat build of Keycloak 26.6Red Hat |
|
Red Hat build of Keycloak 26.6Red Hat |
|
Red Hat build of Keycloak 26.6.4Red Hat | |
Red Hat Build of KeycloakRed Hat | |
Red Hat Build of KeycloakRed Hat | |
Red Hat Data Grid 8Red Hat | |
Red Hat JBoss Enterprise Application Platform Expansion PackRed Hat | |
Red Hat Single Sign-On 7Red Hat |
References
- RHSA-2026:30083vendor-advisory
- RHSA-2026:30084vendor-advisory
- https://access.redhat.com/security/cve/CVE-2026-11800vdb-entry
- RHBZ#2487006issue-tracking
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-11800.json
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