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

Source: https://junglewise.ai/threats/cve-2021-30663-apple-multiple-products-webkit-integer-overflow-vulnerability  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2021-11-03. Updated: 2026-05-10  
License: CC BY 4.0 with a link back

CVE-2021-30663 · Severity: critical · CVSS 8.8 · Exploited in the wild · Published 2021-11-03

An integer overflow vulnerability in WebKit's HTML processing was addressed with improved input validation. Processing maliciously crafted web content may lead to arbitrary code execution on affected Apple devices and software.

Technologies: [Apple Multiple Products](https://junglewise.ai/threats/technologies/multiple-products). Vendors: [Apple](https://junglewise.ai/threats/vendors/apple).

## Quick answers

**Is CVE-2021-30663 exploited in the wild?** Yes. CVE-2021-30663 is known to be exploited in the wild, first recorded on 3 November 2021. Treat it as urgent.

**How severe is CVE-2021-30663?** Critical severity, with a CVSS score of 8.8, published 3 November 2021.

**Which products and versions are affected?** Apple iOS Before 14.5.1, and 12.5.3; Apple iPadOS Before 14.5.1; Apple tvOS Before 14.6; Apple Safari Before 14.1.1; and 2 more.

**Is there a fix for CVE-2021-30663?** A patch was published on 2021-05-03: Fixed in iOS 14.5.1, iPadOS 14.5.1, tvOS 14.6, iOS 12.5.3, Safari 14.1.1, macOS Big Sur 11.3.1 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2021-30663 attacked?** It is attacked over the network or with local access, in a software library.

**Am I affected by CVE-2021-30663?** Check whether you run Apple Multiple Products. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Affected products

- Apple iOS Before 14.5.1, and 12.5.3
- Apple iPadOS Before 14.5.1
- Apple tvOS Before 14.6
- Apple Safari Before 14.1.1
- Apple macOS Big Sur Before 11.3.1
- Apple WebKit All versions used in affected OS releases

## Timeline

- 2021-05-03: patched: Fixed in iOS 14.5.1, iPadOS 14.5.1, tvOS 14.6, iOS 12.5.3, Safari 14.1.1, macOS Big Sur 11.3.1
- 2021-11-03: kev added: Added to CISA Known Exploited Vulnerabilities Catalog
- 2021-11-03: disclosed: Publicly published in NVD

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