Medium

Keycloak has a Time-of-check Time-of-use (TOCTOU) Race Condition

Disclosed: 28.05.2026
Updated: 11.10.2026 12:22

A flaw was found in Keycloak. An authenticated administrator with the manage-clients role can exploit a Time-of-check to time-of-use (TOCTOU) vulnerability in the name-based admin role checks. This allows the attacker to escalate their privileges to realm-admin for all users within the realm, granting them extensive control over the system. The composite role relationship persists even after the attacker's own permissions are revoked and across system reboots.

Affected software

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Platform	Package	Vulnerable versions	Fixed in
Java / Kotlin (Maven)	org.keycloak:keycloak-server	< 26.6.4	26.6.4

References

CVSS score 6.5/10

CVSS vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N
Weakness (CWE): CWE-367
Platform: Java / Kotlin (Maven)
Package: org.keycloak:keycloak-server
Disclosed: 28.05.2026
Updated: 11.10.2026 12:22

Sources and licenses

OSV / GitHub Advisory Database - GHSA-pq65-77rc-7r8c - CC BY 4.0

Vulnerability history: org.keycloak:keycloak-server

All published vulnerabilities of this package (Java / Kotlin (Maven)), newest first. Shows whether this is a one-off slip or a package that needs watching.

This is the only known vulnerability of this package.

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