CVE-2021-1871
Apple iOS, iPadOS, and macOS WebKit Remote Code Execution Vulnerability
- Critical 9.8
- Exploited: added to CISA KEV 3 Nov 2021
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..
Key facts
- Published
- 2 Apr 2021
- Last changed
- 21 Oct 2025
- Assigned by
- apple
- KEV added
- 3 Nov 2021
- KEV fix due
- 17 Nov 2021
- EPSS
- 7.002% likely to be exploited in the next 30 days, higher than 94.26% of CVEs (scores for 15 Nov 2026)
- SSVC (CISA)
- Exploitation: active; Automatable: yes; Technical impact: total
Severity scores
Each score is shown as its source gave it. They are not averaged or merged.
- 9.8CVSS 3.1, Criticalfrom CISA (ADP container)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/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 | iOS and iPadOS |
|
| Apple | macOS |
|
Timeline
- 2 Apr 2021 Published
- 3 Nov 2021 CVE-2021-1871 added to CISA KEV
- 3 Nov 2021 Added to the CISA KEV catalogue