CVE-2020-27921: 
macOS vulnerability analysis and mitigation

CVE-2020-27921 is a security vulnerability discovered in macOS affecting multiple versions including Big Sur 11.0.1, Catalina, and Mojave. The vulnerability was disclosed and patched in December 2020. It involves a race condition in the kernel that could allow a malicious application to execute arbitrary code with kernel privileges (Apple Advisory, Apple Security).

The vulnerability is classified as a race condition that was addressed with improved state handling in the macOS kernel. The CVSS v3.1 base score is 7.0 (HIGH) with the vector string CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H. The vulnerability was discovered by Linus Henze of pinauten.de (NVD).

If exploited, this vulnerability allows a malicious application to execute arbitrary code with kernel privileges, effectively gaining the highest level of system access. This could potentially lead to complete system compromise, allowing an attacker to install programs, create new accounts with full user rights, or view, change, or delete data (Apple Advisory).

The vulnerability requires local access and user interaction to exploit. It affects macOS versions up to Big Sur 11.0.1, Catalina (Security Update 2020-001), and Mojave (Security Update 2020-007) (Apple Security).

Apple has released patches for this vulnerability in macOS Big Sur 11.1, Security Update 2020-001 Catalina, and Security Update 2020-007 Mojave. Users are advised to update their systems to these versions or later to mitigate the vulnerability (Apple Security).