A flaw was found in the HOTP authentication mechanism of the keycloak-services component, which provides identity and access management services. The issue occurs because the system validates a one-time password and updates its internal counter in two separate steps without proper locking. An attacker with a users password could exploit this timing gap to use a single one-time code to log in multiple times simultaneously.
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.