Is CVE-2021-1871 actively exploited?

Yes. Previdian tracks CVE-2021-1871 as a known exploited vulnerability. Confidence is confirmed.

What exploitation activity has Previdian observed?

Previdian has not yet recorded sensor-observed exploitation attempts for CVE-2021-1871. Our sensors continue to monitor for activity targeting this CVE.

Which versions are affected?

CVE-2021-1871 affects Apple iOS and iPadOS, macOS. Reported affected versions include unspecified to < 14.4 and unspecified to < 11.2.

Yes. CVE-2021-1871 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

Vulnerability report

Exploited in the wild Confirmed confidence In CISA KEV

CVE-2021-1871

Q: How should organizations remediate it?

Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.

Q: Is it in CISA KEV?

Yes. CVE-2021-1871 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

iOS and iPadOS

Apple / iOS and iPadOS · affected before 14.4

Watch CVE-2021-1871 Browse KEV feed

Severity: CVSS 9.8 · Critical
Confidence: Confirmed
Exploit status: Exploited in the wild
EPSS: 7.0%
First observed: —
Last observed: —

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2021-1871 is an unauthenticated vulnerability affecting Apple iOS and iPadOS, macOS. A logic issue was addressed with improved restrictions. This issue is fixed in macOS Big Sur 11.2, Security Update 2021-001...

Is it exploited?

Yes. Previdian tracks this CVE as a known exploited vulnerability. Confidence is confirmed. Listed in CISA KEV.

Who is affected?

Apple / iOS and iPadOS affected before 14.4.

What should we do?

Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.

Overview

A logic issue was addressed with improved restrictions

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..

Vendor Product Affected Status

Apple Affected

iOS and iPadOS

Before 14.4

Affected

Apple Affected

macOS

Before 11.2

Affected

View vendor advisory

Published: 02 Apr 2021
Exploitation Reported: 03 Nov 2021
Attack vector: Remote
Complexity: Low
Privileges: None
User interaction: None

CVE References

CVE Record CVE.org · CVE Record https://www.cve.org/CVERecord?id=CVE-2021-1871
FEDORA-2021-864dc37032 lists.fedoraproject.org · Vendor Advisory https://lists.fedoraproject.org/archives/list/package-announce%40list...
DSA-4923 debian.org · Vendor Advisory https://www.debian.org/security/2021/dsa-4923
support.apple.com/en-us/HT212147 support.apple.com · CVE Record https://support.apple.com/en-us/HT212147
support.apple.com/en-us/HT212146 support.apple.com · CVE Record https://support.apple.com/en-us/HT212146

Exploitation evidence

Why Previdian marks this CVE as exploited

Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.

Exploited in the wild

CISA

Recorded 03 Nov 2021

A trusted third party reported exploitation.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the Previdian Pro API.

Learn about Pro API access

Source	Added
CISA First	2021-11-03 00:00 UTC

Detection

Operational artifacts and observed signals

Make the evidence actionable in scanner, SOC, and edge-control workflows.

Observed signals

Request targets
User-Agents
Callback hosts: 0; 0; 0

Request targets and User-Agents available in Pro. Callback host details available in Enterprise.

Scanner coverage

No scanner integrations recorded yet.

Virtual patch status

No Previdian virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.

Learn about virtual patches →

No detection artifacts or sensor request patterns are available for this CVE yet.

Check back as sensor telemetry and scanner integrations are updated.

Risk and context

Severity, weaknesses, and research context

CVSS v3.1

9.8 Critical

Potential damage if exploited. Separate from whether attackers are using it.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS

7.0%

Estimated chance of exploitation in the next 30 days. Previdian's warning comes from evidence, not this score.

All CVSS Scores

CVSS v3.1 9.8 Critical

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS v2.0 7.5 High

AV:N/AC:L/Au:N/C:P/I:P/A:P

Timeline

From disclosure to observed exploitation

03 Nov 2021
00:00 UTC

Added to CISA KEV

Listed in the CISA Known Exploited Vulnerabilities catalog
02 Apr 2021
18:06 UTC

CVE published

Vulnerability disclosed publicly
08 Dec 2020
00:00 UTC

CVE ID reserved

Identifier reserved by the CNA

Pro API

Automate this intelligence

Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.

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Evidence confidence and provenance
First-party sensor telemetry
PoC and scanner references
Affected versions and enrichment
Automation-ready JSON delivery

GET /api/v2/pro/kevs/CVE-2021-1871

Free JSON includes basic KEV fields

{
  "cve_id": "CVE-2021-1871",
  "confidence": "Confirmed",
  "cvss_score": 9.8,
  "cvss_estimated": false,
  "epss_score": 0.07002,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": false
  },
  "sensor_telemetry": { "attempts": 0, "sensors": 0 }
}