CVE-2021-30858

CVE-2021-30858 is a use-after-free memory corruption flaw (CWE-416) in the web content processing component (WebKit) of Apple iOS, iPadOS, and macOS, which Apple addressed with improved memory management. An attacker triggers it by getting a victim to process maliciously crafted web content, typically by visiting or being redirected to an attacker-controlled site, and successful exploitation leads to arbitrary code execution on the victim's device (CVSS 3.1: 8.8 High, network vector with user interaction required). Anyone running affected builds of iOS, iPadOS, or macOS, or the affected component on Fedora or Debian Linux per the CPE data, is exposed, since virtually all Apple devices process web content by default. Apple acknowledged that the flaw was being actively exploited, reportedly as part of NSO Group's 'ForcedEntry' targeted zero-day espionage chain, and CISA added it to the Known Exploited Vulnerabilities catalog on 2021-11-03. No public proof-of-concept is known, but the confirmed in-the-wild use makes rapid patching urgent.

What to do: Update iPhones and iPads to iOS/iPadOS 14.8 and Macs to macOS Big Sur 11.6 immediately, and on Fedora or Debian apply the distribution's updated WebKit packages. Use MDM or inventory data to confirm no managed devices remain on pre-patch builds, since the flaw was exploited as a zero-day in targeted espionage operations. This is a CISA KEV entry (added 2021-11-03), so the catalog's required action of applying vendor updates is mandatory for federal agencies and strongly recommended for everyone else.