CVE-2021-30766

Vulnerability

An out-of-bounds write vulnerability exists in the macOS kernel, specifically in the AMD kernel component. This issue affects macOS Big Sur before version 11.5, macOS Catalina before Security Update 2021-004, and macOS Mojave before Security Update 2021-005. The vulnerability was addressed by improving input validation to prevent memory corruption [1][2][3].

Exploitation

An attacker must have the ability to run a malicious application on the target system. No additional privileges beyond user-level access are required. The application can trigger the out-of-bounds write by sending crafted input to the kernel, leading to memory corruption. The exact exploitation steps are not publicly disclosed, but the vulnerability resides in the AMD kernel component [1][2][3].

Impact

Successful exploitation allows the application to execute arbitrary code with kernel privileges, resulting in full compromise of the system's confidentiality, integrity, and availability. The attacker gains the highest level of privilege, enabling complete control over the affected device [1][2][3].

Mitigation

Apple released fixes on July 21, 2021: macOS Big Sur 11.5, Security Update 2021-004 for Catalina, and Security Update 2021-005 for Mojave. Users should update to these patched versions. No workarounds are available. The vulnerability is not listed on the CISA Known Exploited Vulnerabilities catalog as of the publication date [1][2][3].