A race condition was addressed with improved state handling. This issue is fixed in macOS Monterey 12.0.1, Security Update 2021-007 Catalina, macOS Big Sur 11.6.1. A malicious application may be able to execute arbitrary code with kernel privileges.
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.