ACTIVELY EXPLOITED
CVE-2021-30663: Apple Multiple Products WebKit Integer Overflow Vulnerability
| Vendor | Apple |
|---|---|
| Product | Multiple Products |
| Actively exploited | Yes |
| Added to CISA KEV | 3 Nov 2021 |
| CISA federal deadline | 17 Nov 2021 |
| Weakness (CWE) | CWE-190, CWE-20 |
Required action (CISA's text)
Apply updates per vendor instructions.
Description (NVD)
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.
SOURCES
Other Apple flaws
- CVE-2024-27834: Apple Multiple Products Improper Authentication Vulnerability
- CVE-2026-86950: Apple Multiple Products Out-of-Bounds Write Vulnerability
- CVE-2026-65400: Apple macOS Improper Authentication Vulnerability
- CVE-2025-43520: Apple Multiple Products Classic Buffer Overflow Vulnerability
- CVE-2025-43510: Apple Multiple Products Improper Locking Vulnerability
Data from NVD, CISA KEV, FIRST EPSS and vendor advisories. Updated 10 Nov 2026.