Home/CVE/Apple iOS, iPadOS, and macOS WebKit Remote Code Execution Vulnerability
CVE

CVE-2021-1871

Apple iOS, iPadOS, and macOS WebKit Remote Code Execution Vulnerability

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..

CRITICAL · CVSS 9.8 ⚠ CISA KEV EPSS 0.00484
Act now
  • Listed on CISA KEV (known exploited in the wild)
  • SSVC exploitation status: active
  • SSVC automatable: yes - attacks can be scripted at scale
  • CVSS base score ≥ 7.0
Sigma rules8 YARA rules0
⬢

Required Remediation

Apply updates per vendor instructions.

▤

Affected Products & Versions

7
apple ipados< 14.4
apple iphone os< 14.4
apple mac os x>= 10.15 and < 10.15.7
apple mac os xall versions
apple macos>= 11.0.1 and < 11.2
debian linuxall versions
fedoraproject fedoraall versions
◈

Sigma Hunt Rules

8
Exact rules name this CVE ID. Product rules name an affected product in their title. Related rules cover techniques used by actors who exploited this CVE. Showing the most relevant matches; the complete related set is on the full drill-down.
producthighSuspicious Microsoft Office Child Process - MacOS
producthighRemote Access Tool - Renamed MeshAgent Execution - MacOS
producthighBinary Padding - MacOS
productmediumSuspicious Execution via macOS Script Editor
productmediumSystem Information Discovery Via Sysctl - MacOS
productmediumNew File Exclusion Added To Time Machine Via Tmutil - MacOS
▣

Scoring & Timeline

9.8
CRITICAL · CVSS v3.1 · product-security@apple.com
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD02 Apr 2021 · 07:15 PM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
SSVC triage · cisa-vulnrichment
Exploitation
active
Automatable
yes
Technical impact
total
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
⚑

Vendor Advisories

13
rhsaRHSA-2025:10364Important
suse-csafSUSE-SU-2022:0182-2
suse-csafopenSUSE-SU-2022:0182-1
suse-csafSUSE-SU-2022:0182-1
suse-csafSUSE-SU-2022:0183-1
🔗

References & Sources

5
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/L3L6ZZOU5JS7E3RFYGLP7UFLXCG7TNLU/Broken LinkMailing List
https://support.apple.com/en-us/HT212146Release NotesVendor Advisory
https://support.apple.com/en-us/HT212147Release NotesVendor Advisory
https://www.debian.org/security/2021/dsa-4923Mailing ListThird Party Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-1871US Government Resource
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