CVEvulnerability
CVE-2026-9704
8.8 HIGH
Official page ↗
- Status
- Modified
- Published
- 2026-05-27
- Last modified
- 2026-06-26
- Assigner
- [email protected]
- CVSS 3.1 ([email protected])
- 6.8 MEDIUM — CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N
- CVSS 3.1 ([email protected])
- 8.8 HIGH — CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Weaknesses
- CWE-1284
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.
Affected configurations
• redhat build of keycloak
Related
Weakness · CWE (1)
- CWE-1284 Improper Validation of Specified Quantity in Input weakness
References
- https://access.redhat.com/errata/RHSA-2026:25097 access.redhat.com
- https://access.redhat.com/errata/RHSA-2026:25098 access.redhat.com
- https://access.redhat.com/errata/RHSA-2026:30049 access.redhat.com
- https://access.redhat.com/errata/RHSA-2026:30050 access.redhat.com
- https://access.redhat.com/security/cve/CVE-2026-9704 Mitigation, Vendor Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=2481877 Issue Tracking, Vendor Advisory