# CVE-2021-1870: Apple iOS, iPadOS, and macOS WebKit Remote Code Execution Vulnerability

> CVE-2021-1870: Apple iOS, iPadOS, and macOS WebKit Remote Code Execution Vulnerability. CVSS 9.8 (CVSS 3.1), in CISA KEV.

Canonical: https://rewindex.com/cve/CVE-2021-1870
Last updated: 2025-10-21T23:25:49Z

- Published: 2021-04-02 18:06 UTC · Updated: 2025-10-21 23:25 UTC · Assigner: apple
- CVSS: 9.8 (CVSS 3.1) · Severity: Critical · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS: 7.7%, 95th percentile (scored 2026-10-25)
- CISA KEV: yes, added 2021-11-03, federal due date 2021-11-17, ransomware use: Unknown

## Description

A logic issue was addressed with improved restrictions. This issue is fixed in macOS Big Sur 11.2, Security Update 2021-001 Catalina, Security Update 2021-001 Mojave, iOS 14.4 and iPadOS 14.4. A remote attacker may be able to cause arbitrary code execution. Apple is aware of a report that this issue may have been actively exploited..

## CISA required action

Apply updates per vendor instructions.

## Affected vendors and products

- Apple: iOS and iPadOS
- Apple: macOS

## References

- [CVE record on cve.org](https://www.cve.org/CVERecord?id=CVE-2021-1870)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2021-1870)
- [https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JN6ZOD62CTO54CHTMJTHVEF6R2Y532TJ/](https://lists.fedoraproject.org/archives/list/package-announce%2540lists.fedoraproject.org/message/JN6ZOD62CTO54CHTMJTHVEF6R2Y532TJ/)
- [https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/L3L6ZZOU5JS7E3RFYGLP7UFLXCG7TNLU/](https://lists.fedoraproject.org/archives/list/package-announce%2540lists.fedoraproject.org/message/L3L6ZZOU5JS7E3RFYGLP7UFLXCG7TNLU/)
- [https://security.gentoo.org/glsa/202104-03](https://security.gentoo.org/glsa/202104-03)
- [https://support.apple.com/en-us/HT212146](https://support.apple.com/en-us/HT212146)
- [https://support.apple.com/en-us/HT212147](https://support.apple.com/en-us/HT212147)

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_Sources: CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (https://www.cve.org/) This product uses data from the NVD API but is not endorsed or certified by the NVD. (https://nvd.nist.gov/) Known Exploited Vulnerabilities catalog from CISA. (https://www.cisa.gov/known-exploited-vulnerabilities-catalog) EPSS scores from FIRST (Exploit Prediction Scoring System). (https://www.first.org/epss/)_


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Canonical: https://rewindex.com/cve/CVE-2021-1870 · Markdown: https://rewindex.com/cve/CVE-2021-1870.md · JSON: https://rewindex.com/api/v1/cves/CVE-2021-1870 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T03:10:14.386Z