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CVE PROGRAM SOURCE RECORD6.8 Medium

CVE-2026-9704

Keycloak: keycloak: privilege escalation due to oversized subject_token jwt

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Status
Published
Published
Updated
Assigning organization
redhat

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 products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Red Hat Red Hat build of Keycloak 26.4

Default version status: affected

  • 26.4.13-1 to < *unaffected

Red Hat Red Hat build of Keycloak 26.4

Default version status: affected

  • 26.4-19 to < *unaffected

Red Hat Red Hat build of Keycloak 26.4

Default version status: affected

  • 26.4-19 to < *unaffected

Red Hat Red Hat build of Keycloak 26.4.13

Default version status: unaffected

Red Hat Red Hat build of Keycloak 26.6

Default version status: affected

  • 26.6.3-3 to < *unaffected

Red Hat Red Hat build of Keycloak 26.6

Default version status: affected

  • 26.6-6 to < *unaffected

Red Hat Red Hat build of Keycloak 26.6

Default version status: affected

  • 26.6-6 to < *unaffected

Red Hat Red Hat build of Keycloak 26.6.3

Default version status: unaffected

References