GitHub Advisoryadvisory · Maven
GHSA-rr5q-3xwr-f323 Keycloak Vulnerable to Improper Validation of Specified Quantity in Input
MEDIUM
Official page ↗
- Aliases
- CVE-2026-9704
- Ecosystem
- Maven
- Packages
- org.keycloak:keycloak-server-spi-private, org.keycloak:keycloak-services
- Severity
- Moderate
- CVSS vector
- CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N
- Weaknesses
- CWE-1284
- Reviewed
- 2026-07-01
Affected packages
• Maven org.keycloak:keycloak-server-spi-private: < 26.6.3 → fixed in 26.6.3
• Maven org.keycloak:keycloak-services: < 26.6.3 → fixed in 26.6.3
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.
Related
Alias · CVE (1)
- CVE-2026-9704 A flaw was found in Keycloak. vulnerability
Weakness · CWE (1)
- CWE-1284 Improper Validation of Specified Quantity in Input weakness
References
- https://nvd.nist.gov/vuln/detail/CVE-2026-9704 advisory
- https://github.com/keycloak/keycloak/issues/49435 web
- https://github.com/keycloak/keycloak/pull/49472 web
- https://github.com/keycloak/keycloak/commit/f1e5b7776c42938d0782fd5846346b8f75c815e6 web
- https://access.redhat.com/errata/RHSA-2026:25097 web
- https://access.redhat.com/errata/RHSA-2026:25098 web
- https://access.redhat.com/errata/RHSA-2026:30049 web
- https://access.redhat.com/errata/RHSA-2026:30050 web
- https://access.redhat.com/security/cve/CVE-2026-9704 web
- https://bugzilla.redhat.com/show_bug.cgi?id=2481877 web
- https://github.com/keycloak/keycloak package