Improper Validation of Specified Quantity in Input Affecting keycloak-25 package, versions <25.0.6+e2


Severity

Recommended
0.0
high
0
10

Snyk's Security Team recommends NVD's CVSS assessment. Learn more

Threat Intelligence

EPSS
0.59% (46th percentile)

Do your applications use this vulnerable package?

In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.

Test your applications
  • Snyk IDSNYK-ECHOLATEST-KEYCLOAK25-19435056
  • published31 Aug 2026
  • disclosed27 May 2026

Introduced: 27 May 2026

CVE-2026-9704  (opens in a new tab)
CWE-1284  (opens in a new tab)

How to fix?

Upgrade Echo:latest keycloak-25 to version 25.0.6+e2 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream keycloak-25 package and not the keycloak-25 package as distributed by Echo. See How to fix? for Echo:latest relevant fixed versions and status.

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 Base Scores

version 3.1