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CVE-2021-30663

HIGH severity · CVSS 8.8 · Integer overflow · actively exploited (CISA KEV)
8.8CVSS HIGH ● exploited
🔴 Actively exploited in the wild (CISA Known Exploited Vulnerabilities). Added to KEV 2021-11-03. US federal agencies must patch by 2021-11-17.

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.

Impact & exploitability

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionRequired
Confidentiality impactHigh
Integrity impactHigh
Availability impactHigh
Exploit probability (EPSS)1%

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Affected products we track (1)

Recommendation

This vulnerability is being actively exploited in the wild — patch affected products urgently. Open any affected product above for its exact safe version.

Last checked: Wed, 10 Jun 2026 22:18:30 UTC