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.
History

Thu, 25 Jun 2026 21:30:00 +0000

Type Values Removed Values Added
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.
Title Org.keycloak:keycloak-services: keycloak: authentication bypass via jwt algorithm confusion
First Time appeared Redhat
Redhat build Keycloak
Redhat jboss Data Grid
Redhat jbosseapxp
Redhat red Hat Single Sign On
Weaknesses CWE-347
CPEs cpe:/a:redhat:build_keycloak:
cpe:/a:redhat:build_keycloak:26.6::el9
cpe:/a:redhat:jboss_data_grid:8
cpe:/a:redhat:jbosseapxp
cpe:/a:redhat:red_hat_single_sign_on:7
Vendors & Products Redhat
Redhat build Keycloak
Redhat jboss Data Grid
Redhat jbosseapxp
Redhat red Hat Single Sign On
References
Metrics cvssV3_1

{'score': 8.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N'}


cve-icon MITRE

Status: PUBLISHED

Assigner: redhat

Published: 2026-06-25T20:57:05.276Z

Updated: 2026-06-25T20:57:05.276Z

Reserved: 2026-06-09T14:06:04.695Z

Link: CVE-2026-11800

cve-icon Vulnrichment

No data.

cve-icon NVD

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cve-icon Redhat

No data.