CVE-2026-9704

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.

Score
CVSS 3.1 8.8 High
Status
Modified - secalert@redhat.com
Published
2026-05-27
Last modified
2026-06-26
Weaknesses
CWE-1284

Affected products

References

 
 
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