CVE-2026-9704: Improper Validation of Specified Quantity in Input in Red Hat Red Hat Build of Keycloak
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.
CVE-2026-9704: Improper Validation of Specified Quantity in Input in Red Hat Red Hat Build of Keycloak
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.
CVSS v3.1
Score 6.8medium
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- redhat
- Date Reserved
- 2026-05-27T12:39:12.284Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
- Vendor Advisory Urls
- [{"url":"https://access.redhat.com/security/cve/CVE-2026-9704","vendor":"Red Hat"}]
Threat ID: 6a16f9eae29bf47b50c0f5c1
Added to database: 5/27/2026, 2:04:26 PM
Last updated: 5/27/2026, 2:05:23 PM
Views: 1
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