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.

• CWE-1284

• https://access.redhat.com/errata/RHSA-2026:25097
• https://access.redhat.com/errata/RHSA-2026:25098
• https://access.redhat.com/errata/RHSA-2026:30049
• https://access.redhat.com/errata/RHSA-2026:30050
• https://access.redhat.com/security/cve/CVE-2026-9704Mitigation, Vendor Advisory
• https://bugzilla.redhat.com/show_bug.cgi?id=2481877Issue Tracking, Vendor Advisory

Published

May 27, 2026

Last Modified

Jun 26, 2026

Status

Modified

• How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
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