Vulnerability Details 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.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.0
EPSS Ranking 14.1%
CVSS Severity
CVSS v3 Score 6.8
References
Products affected by CVE-2026-9704
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cpe:2.3:a:redhat:build_of_keycloak:-