This vulnerability allows local attackers to escalate privileges on vulnerable installations of Apple macOS. An attacker must first obtain the ability to execute low-privileged code on the target system in order to exploit this vulnerability.
The specific flaw exists within the nsurlstoraged service. The issue results from the lack of proper validation of a reference count, which can result in an integer overflow when incrementing it. An attacker can leverage this vulnerability to escalate privileges under the context of the current service.