What’s Vulnerable › Vulnerabilities

CVE-2021-30663: Apple Multiple Products WebKit Integer Overflow Vulnerability

• Severity: high (CVSS 8.8 v3.1)
• Exploited in the wild: yes — in CISA KEV since 2021-11-03
• EPSS: 3.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-09-08 · updated 2026-06-17
• Weakness: CWE-190

Description

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.

Affected products

• Apple iPadOS: from 14.0 before 14.5.1 — fixed in 14.5.1
• Apple Iphone Os: before 12.5.3; from 14.0 before 14.5.1 — fixed in 12.5.3, 14.5.1
• Apple macOS: from 11.0 before 11.3.1 — fixed in 11.3.1
• Apple Safari: before 14.1.1 — fixed in 14.1.1
• Apple tvOS: before 14.6 — fixed in 14.6

How to fix

Upgrade to a fixed version: Apple iPadOS 14.5.1; Apple Iphone Os 12.5.3, 14.5.1; Apple macOS 11.3.1; Apple Safari 14.1.1; Apple tvOS 14.6. Check the vendor advisory for mitigations.

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://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

Get alerted when CVE-2021-30663 or the next vulnerability affects your stack