MEDIUM 6.8
GHSA-rr5q-3xwr-f323
Keycloak Vulnerable to Improper Validation of Specified Quantity in Input
Details
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.
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Affected packages
Maven / org.keycloak:keycloak-server-spi-private
Introduced in:
0 Fixed in: 26.6.3 Fix
# pom.xml: bump <version>26.6.3</version> for org.keycloak:keycloak-server-spi-private Maven / org.keycloak:keycloak-services
Introduced in:
0 Fixed in: 26.6.3 Fix
# pom.xml: bump <version>26.6.3</version> for org.keycloak:keycloak-services 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]