CVE-2021-1857: 
macOS vulnerability analysis and mitigation

CVE-2021-1857 is a memory initialization vulnerability that was discovered in Apple's CFNetwork component. The vulnerability was disclosed and patched in April 2021, affecting multiple Apple products including iOS 14.5, iPadOS 14.5, macOS Big Sur 11.3, iTunes 12.11.3 for Windows, iCloud for Windows 12.3, tvOS 14.5, and watchOS 7.4 (Apple Security).

The vulnerability is classified as a memory initialization issue in CFNetwork that was addressed with improved memory handling. It received a CVSS v3.1 Base Score of 6.5 (MEDIUM) with a vector string of CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N (NVD).

When exploited, the vulnerability could allow processing of maliciously crafted web content to disclose sensitive user information (Apple Security).

Apple addressed this vulnerability by implementing improved memory handling in CFNetwork. Users should update to the following versions: iOS 14.5, iPadOS 14.5, macOS Big Sur 11.3, iTunes 12.11.3 for Windows, iCloud for Windows 12.3, tvOS 14.5, watchOS 7.4, Security Update 2021-002 Catalina, or Security Update 2021-003 Mojave (Apple Security).