CISA-confirmed known exploited vulnerability

CVE-2021-30663

Apple Multiple Products WebKit Integer Overflow Vulnerability

Apple · Multiple Products

Vulnerability details

Apple iOS, iPadOS, macOS, tvOS, and Safari WebKit contain an integer overflow vulnerability that leads to code execution when processing maliciously crafted web content. This vulnerability could impact HTML parsers that use WebKit, including but not limited to Apple Safari and non-Apple products which rely on WebKit for HTML processing.

Added to CISA KEV: 2021-11-03

Ransomware campaign use: Unknown

CISA due date: 2021-11-17

Defensive guidance from CISA

Apply updates per vendor instructions.

This is the source's required-action field, not an independently validated patch procedure. Refer to the vendor for exact affected versions and fixes.

Source catalog date: 2026-11-06T19:44:45.1797Z · Last retrieved: 2026-11-06 21:02:26 UTC

View CISA KEV catalog View NVD record

← All vulnerabilities