CVE DATABASE / CVE-2021-30663
CVE-2021-30663
Apple Multiple Products WebKit Integer Overflow Vulnerability
CVSS 8.8 · HIGH
⚠ CISA KEV — ACTIVELY EXPLOITED
On the CISA KEV catalog
Confirmed exploited in the wild. Added 2021-11-03.
Federal remediation due 2021-11-17.
Required action: Apply updates per vendor instructions.
Summary
An integer overflow was addressed with improved input validation. This issue is fixed in iOS 14.5.1 and iPadOS 14.5.1, tvOS 14.6, iOS 12.5.3, Safari 14.1.1, macOS Big Sur 11.3.1. Processing maliciously crafted web content may lead to arbitrary code execution.
CVSS 3.1 breakdown
| Base score | 8.8 (HIGH) |
| Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H |
| Attack vector | NETWORK |
| Attack complexity | LOW |
| Privileges required | NONE |
| User interaction | REQUIRED |
| Scope | UNCHANGED |
| Confidentiality | HIGH |
| Integrity | HIGH |
| Availability | HIGH |
Weakness type (CWE)
Affected products
Apple safariApple ipadosApple iphone osApple macosApple tvos
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References
- https://support.apple.com/en-us/HT212335
- https://support.apple.com/en-us/HT212336
- https://support.apple.com/en-us/HT212341
- https://support.apple.com/en-us/HT212532
- https://support.apple.com/en-us/HT212534
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-30663
Data: NIST NVD + CISA KEV. NVD last modified 2025-10-23. Always verify against the vendor advisory before acting.