MariaDB server is a community developed fork of MySQL server. From 10.6.1 until 10.6.28, 10.11.19, 11.4.13, 11.8.9, 12.3.3, and 13.0.2, MariaDB's ACL cache could generate the same database-privilege cache key for role and localhost user names that matched because both used an empty IP component. An attacker with CREATE USER could create the colliding principal and, when the original principal's database privileges were cached, exercise privileges assigned to the other account. This issue is fixed in versions 10.6.28, 10.11.19, 11.4.13, 11.8.9, 12.3.3, and 13.0.2.