CVE-2021-30663
Apple Multiple Products WebKit Integer Overflow Vulnerability
- High 7.8
- Exploited: added to CISA KEV 3 Nov 2021
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.
Key facts
- Published
- 8 Sep 2021
- Last changed
- 21 Oct 2025
- Assigned by
- apple
- KEV added
- 3 Nov 2021
- KEV fix due
- 17 Nov 2021
- EPSS
- 3.521% likely to be exploited in the next 30 days, higher than 89.418% of CVEs (scores for 15 Nov 2026)
- SSVC (CISA)
- Exploitation: active; Automatable: no; Technical impact: total
Severity scores
Each score is shown as its source gave it. They are not averaged or merged.
- 7.8CVSS 3.1, Highfrom CISA (ADP container)
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
What to do
- Apply updates per vendor instructions.CISA KEV required action
Historical context and remediation
This reference retains the original CVE publication date. A recent record update does not mean a new attack occurred.
No separately sourced impact summary is available on this page yet. Consult the description, version data and dated exploitation evidence.
Version statuses below come from the CNA. An “unaffected” version is not necessarily a currently supported release or proof of a patch date. EPSS is a dated risk estimate, not a count of historical attacks.
Affected products
| Vendor | Product | Versions |
|---|---|---|
| Apple | macOS |
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| Apple | macOS |
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| Apple | macOS |
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| Apple | macOS |
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| Apple | macOS |
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Timeline
- 8 Sep 2021 Published
- 3 Nov 2021 CVE-2021-30663 added to CISA KEV
- 3 Nov 2021 Added to the CISA KEV catalogue