CVE-2026-11800
Org.keycloak:keycloak-services: keycloak: authentication bypass via jwt algorithm confusion
CVSS Score
8.1
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-347 |
| Vendor | red hat |
| Product | red hat build of keycloak 26.6 |
| Published | Jun 25, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None
Affected Versions
Red Hat / Red Hat build of Keycloak 26.6
All versions affected Red Hat / Red Hat build of Keycloak 26.6
All versions affected Red Hat / Red Hat build of Keycloak 26.6
All versions affected Red Hat / Red Hat build of Keycloak 26.6.4
All versions affected Red Hat / Red Hat Build of Keycloak
All versions affected Red Hat / Red Hat Build of Keycloak
All versions affected Red Hat / Red Hat Data Grid 8
All versions affected Red Hat / Red Hat JBoss Enterprise Application Platform Expansion Pack
All versions affected Red Hat / Red Hat Single Sign-On 7
All versions affected References
Credits
Red Hat would like to thank Bilal Teke for reporting this issue.