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.

There are packages installed that are affected by a vulnerability referenced in the following CVE:

  - 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)

ID	Name	Product	Family	Type	Severity
459338	Echo: org.keycloak:keycloak-server-spi-private: security update to 26.6.3	Tenable Cloud Security	Echo Local Security Checks	Local	high
459338	Echo: org.keycloak:keycloak-server-spi-private: security update to 26.6.3	Tenable Self-Hosted Container Security	Echo Local Security Checks	Local	high
444226	SCA: security update for org.keycloak:keycloak-server-spi-private, org.keycloak:keycloak-services (GHSA-rr5q-3xwr-f323)	Tenable Cloud Security	SCA Checks	Local	high
444226	SCA: security update for org.keycloak:keycloak-server-spi-private, org.keycloak:keycloak-services (GHSA-rr5q-3xwr-f323)	Tenable Self-Hosted Container Security	SCA Checks	Local	high

Detections

Analytics

CVE-2026-9704

high

Tenable Plugins

high

high

high

high