Shearwater SecurEnvoy SecurAccess Enrol before 9.4.515 is intended to disable accounts that have had more than 10 failed authentication attempts, but instead allows hundreds of failed authentication attempts, because concurrent attempts are mishandled.
The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.