CVE-2026-9704
MEDIUM
NVD
CVSS Score
6.8
Severity
MEDIUM
Published
May 27, 2026
Vendor
unknown
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.