# CVE-2021-1871: Apple iOS, iPadOS, and macOS WebKit Remote Code Execution Vulnerability

Source: https://junglewise.ai/threats/cve-2021-1871-apple-ios-ipados-and-macos-webkit-remote-code-execution  
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-2021-1871 · Severity: critical · CVSS 9.8 · Exploited in the wild · Published 2021-11-03

A logic issue in the WebKit engine allows remote attackers to execute arbitrary code on affected Apple devices. The vulnerability stems from insufficient restrictions during HTML processing and has been reported as being actively exploited in the wild.

Technologies: [Apple iPadOS](https://junglewise.ai/threats/technologies/ipados), [Apple macOS](https://junglewise.ai/threats/technologies/macos). Vendors: [Apple](https://junglewise.ai/threats/vendors/apple).

## Quick answers

**Is CVE-2021-1871 exploited in the wild?** Yes. CVE-2021-1871 is known to be exploited in the wild, first recorded on 3 November 2021. Treat it as urgent.

**How severe is CVE-2021-1871?** Critical severity, with a CVSS score of 9.8, published 3 November 2021.

**Which products and versions are affected?** Apple iOS before 14.4; Apple iPadOS before 14.4; Apple macOS Big Sur before 11.2; Apple macOS Catalina before Security Update 2021-001; and 2 more.

**Is there a fix for CVE-2021-1871?** A patch was published on 2021-01-26: Fixed in iOS 14.4, iPadOS 14.4, and macOS Big Sur 11.2 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2021-1871 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2021-1871?** Check whether you run Apple iPadOS or Apple macOS. 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 14.4
- Apple iPadOS before 14.4
- Apple macOS Big Sur before 11.2
- Apple macOS Catalina before Security Update 2021-001
- Apple macOS Mojave before Security Update 2021-001
- Apple WebKit

## Timeline

- 2021-11-03: disclosed
- 2021-11-03: kev added: Added to CISA Known Exploited Vulnerabilities Catalog
- 2021-01-26: patched: Fixed in iOS 14.4, iPadOS 14.4, and macOS Big Sur 11.2
- 2021-11-03: exploited: Apple is aware of reports of active exploitation.

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