The Jamf Protect detections team observed this exploit being used in the wild by a variant of the Shlayer adware dropper, as early as January 9th, 2021.
Vulnerable component: macOS
CVSSv3 score: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:H/RL:O/RC:C
CWE-ID: CWE-254 - Security Features
The vulnerability allows a remote attacker to bypass implemented security restrictions.
The vulnerability exists due to a logic issue within the Gatekeeper checks. A remote attacker can craft a specially crafted payload that is not checked by Gatekeeper and bypasses File Quarantine and Application Notarization protections as well. As a result, a malicious binary can be executed on the system.
Note, the vulnerability is being actively exploited in the wild.