CVE-2026-9704

medium Red Hat
CVSS v3 Base Score
6.8
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N
Attack Characteristics
Attack Vector
Network
Attack Complexity
High
Privileges Required
Low
User Interaction
None
Confidentiality
High
Integrity
High
Availability
None
Published: May 27, 2026 (43 days ago)
Last Modified: May 27, 2026
Vendor: Red Hat
Source: REDHAT

Description

A flaw was found in Keycloak. An authenticated user with low privileges can exploit this vulnerability by sending an oversized subject_token JSON Web Token (JWT) to the TokenEndpoint. When the token exceeds a 4000-character limit, it is silently dropped, causing the system to fall back to client credentials. This allows the user to gain the permissions of the client's service account, leading to privilege escalation.

CWE

CWE-1284

Affected Products

Red Hat Build of Keycloak

References

🔗 bugzilla.redhat.com 🔗 www.cve.org 🔗 nvd.nist.gov