CVE-2021-1776: 
macOS vulnerability analysis and mitigation

CVE-2021-1776 is an out-of-bounds write vulnerability discovered in Apple's CoreGraphics component. The vulnerability was disclosed and patched in February 2021, affecting multiple Apple operating systems including macOS Big Sur 11.0.1, macOS Catalina 10.15.7, macOS Mojave 10.14.6, iOS 14.4, iPadOS 14.4, watchOS 7.3, and tvOS 14.4. The vulnerability was discovered by Ivan Fratric of Google Project Zero (Apple Security).

The vulnerability is classified as an out-of-bounds write issue in the CoreGraphics component that occurs when processing maliciously crafted font files. The issue was addressed by Apple through improved bounds checking implementation. The vulnerability has a CVSS v3.1 base score of 7.8 (HIGH) with the vector string CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H (NVD).

When exploited, this vulnerability could allow an attacker to execute arbitrary code on the target system through processing a maliciously crafted font file. The successful exploitation could lead to unauthorized code execution with potential system compromise (Apple Security).

Apple addressed this vulnerability by releasing security updates across multiple platforms: macOS Big Sur 11.2, Security Update 2021-001 Catalina, Security Update 2021-001 Mojave, watchOS 7.3, tvOS 14.4, iOS 14.4 and iPadOS 14.4. Users are advised to update their devices to these versions or later to protect against this vulnerability (Apple Security).