CVE-2026-9704
Last modified
CVE-2026-9704 is a high-severity vulnerability rated 8.8/10 on the CVSS scale. 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. EPSS estimates a 0.32% chance of exploitation in the next 30 days.
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.
Metrics
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Redhat | Build Of Keycloak | All versions |
References
- https://access.redhat.com/security/cve/CVE-2026-9704Mitigation, Vendor Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=2481877Issue Tracking, Vendor Advisory
Timeline
- Published
- Last Modified
- Status
- Modified
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