CVE-2021-1871

highpriority · act · 90OT risk · criticalKEV · exploitedEPSS 0.070 · 94 %ileEURUUS

grimoire priorityP0 · Act now

Exploitable?

Yes · in the wild

CISA KEV

Likely / severe?

7.00% (94th) EPSS

CVSS 7.5 · high

Is it mine?

18 products

Check your exposure

Who says so?

4 sources

cnnvd · enisa_euvd · fstec_bdu · nvd

added 2021-11-03remediate by 2021-11-17

required action Apply updates per vendor instructions.

EPSS · scored 2026-10-23

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..

cvss

Technical severity, 0–10. One row per scoring source.

9.8

010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · high–critical · 7.5–9.8

v2.07.5highAV:N/AC:L/Au:N/C:P/I:P/A:Pprimary · NVD / NIST USexploitability 10 · impact 6.4

v3.19.8criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hprimary · NVD / NIST USexploitability 3.9 · impact 5.9

v3.18.8highAV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:Hsecondary · FSTEC (BDU) RU

v3.19.8criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsecondary · ENISA EU

v3.19.8criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsecondaryexploitability 3.9 · impact 5.9

v3.19.8criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:Hsecondary · CVSS-BT (t0sche)

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Exploitation: active · Automatable: yes · Technical Impact: totalcoordinatorcisa_ssvcUS

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-119USCWE-840US

affected products (18)

Products and version ranges known to be affected.

Apple iOS and iPadOSunspecified → 14.4enisa_euvdEU
Apple macOSunspecified → 11.2enisa_euvdEU
Apple Inc. MacOS≤ 10.15.7fstec_bduRU
Apple Inc. MacOS≤ 11.2fstec_bduRU
Apple Inc. MacOS≤ 10.14.6fstec_bduRU
Apple Inc. iOS≤ 14.4fstec_bduRU
Apple Inc. iPadOS≤ 14.4fstec_bduRU
Fedora Project Fedora≤ 33fstec_bduRU
Red Hat Inc. Red Hat Enterprise Linux≤ 8fstec_bduRU
АО «НППКТ» ОСОН ОСнова Оnyx≤ 2.1fstec_bduRU
Сообщество свободного программного обеспечения WebKitGTK≤ 2.32.0fstec_bduRU
apple ipados< 14.4nvdUScpe:2.3:o:apple:ipados:*:*:*:*:*:*:*:*
apple iphone os< 14.4nvdUScpe:2.3:o:apple:iphone_os:*:*:*:*:*:*:*:*
apple mac os x10.15 → 10.15.7nvdUScpe:2.3:o:apple:mac_os_x:*:*:*:*:*:*:*:*
apple mac os x= 10.15.7nvdUScpe:2.3:o:apple:mac_os_x:*:*:*:*:*:*:*:*
apple macos11.0.1 → 11.2nvdUScpe:2.3:o:apple:macos:*:*:*:*:*:*:*:*
debian debian linux= 10.0nvdUScpe:2.3:o:debian:debian_linux:*:*:*:*:*:*:*:*
fedoraproject fedora= 33nvdUScpe:2.3:o:fedoraproject:fedora:*:*:*:*:*:*:*:*

also known as (4)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd fstec_bdu nvd NVD CVE.org MITRE

published 2021-04-02modified 2026-06-17

references (29)

External citations — patches, advisories, analysis.

scry

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