9.8

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

CVSS: 9.8v3.1CriticalKEVAnalyzed
AliasesUBUNTU-CVE-2021-1871DEBIAN-CVE-2021-1871
Published 02-04-2021Last modified 21-10-2025
Open JSON

Vulnerability summary

CVE-2021-1871 is a critical (CVSS 9.8) vulnerability in Apple iOS, iPadOS, and macOS. It is known to be exploited: CISA lists it, first on 03-11-2021. EPSS estimates a 7.00% chance of exploitation in the next 30 days, higher than 94% of scored vulnerabilities.

Overall risk
85/100
0100
Critical · default modelHow is this calculated?
CVSS score
9.8/10
010
Critical · v3.1 (CVE.org)
EPSS score
7.00%
0%100%
Low · 0.00 pp in 30 days
KEVListedCISA
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 14 · Related 10
DSA-4923-1MGASA-2021-0181OPENSUSE-SU-2021:0637-1OPENSUSE-SU-2022:0182-1RHSA-2021:4381RHSA-2025:10364

Timeline

  1. 02-04-2021
    PublishedVulnerability first disclosed.
  2. 03-11-2021
    Added to CISA KEVApple iOS, iPadOS, and macOS WebKit Remote Code Execution Vulnerability
  3. 17-11-2021
    CISA remediation dueApply updates per vendor instructions.
  4. 21-10-2025
    Last modifiedVulnerability information updated.

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..

CVSS metrics

5 scores · 4 sources · 2 versions

EPSS trend

Probability

7.00%

Chance of exploitation in the next 30 days

Percentile

94%

Versus all other CVEs

30-day change

0.00 pp

From 7.00% on 18-09-2026

18-09-202618-10-2026
EPSS score
7.00%

Known exploited

Compare KEV catalogs
CISA KEVListed
Added
03-11-2021
Federal due date
17-11-2021

CISA required action

Apply updates per vendor instructions. nvd.nist.gov/vuln/detail/CVE-2021-1871

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

No weakness data has been published for this record.

Affected systems

Apple5 products
  • ios and ipados≥ unspecified, < 14.4
  • ipados< 14.4
  • iphone_os< 14.4
  • mac_os_x≥ 10.15, < 10.15.7 | 10.15.7 | 10.15.7:security_update_2020 | 10.15.7:supplemental_update
  • macos≥ unspecified, < 11.2 | ≥ 11.0.1, < 11.2
Ubuntu5 products
  • qtwebkit-opensource-srcAll versions (No fix recorded)
  • qtwebkit-sourceAll versions (No fix recorded)
  • webkit2gtkAll versions (No fix recorded) | < 2.32.0-0ubuntu0.18.04.1 | < 2.32.0-0ubuntu0.20.04.1
  • webkitgtkAll versions (No fix recorded)
  • wpewebkitAll versions (No fix recorded)
Debian3 products
Fedoraproject1 product

4 vendors · 14 products

References

11 links
Show all 11 references