CVE-2021-1870Known exploitationNetwork attack vector

Remote code execution via undisclosed WebKit logic flaw

Published Apr 2, 2021 · Updated Oct 21, 2025

Remote code execution in Apple iOS and iPadOS before 14.4 and macOS before 11.2 allows remote attackers to execute arbitrary code. The WebKit component enforces insufficient restrictions because of a logic error; Apple has not disclosed the affected code path or the restriction that fails. The attack is unauthenticated and network-reachable, and successful exploitation runs arbitrary code; CISA lists the flaw as known exploited.

CVSS severity9.8
Critical
EPSS probability7.71%
Next 30 days · Sep 16, 2026
Known exploitationReported
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Remote code execution in Apple iOS and iPadOS before 14.4 and macOS before 11.2 allows remote attackers to execute arbitrary code. The WebKit component enforces insufficient restrictions because of a logic error; Apple has not disclosed the affected code path or the restriction that fails. The attack is unauthenticated and network-reachable, and successful exploitation runs arbitrary code; CISA lists the flaw as known exploited.

The record

CVE
CVE-2021-1870
Published
Apr 2, 2021
Updated
Oct 21, 2025
Vendor
Apple
Product
iOS and iPadOS
Classifications
T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 2, 2021CVE publishedPublication date reported by the CVE source.
  2. Oct 21, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=unspecified <14.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Apple · iOS and iPadOSversion=unspecified <14.4
Apple · macOSversion=unspecified <11.2

Published CVSS scores

9.8CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.5NVDAV:N/AC:L/Au:N/C:P/I:P/A:P
9.8NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationReported
Public exploitUnconfirmed

Weakness, pattern, technique

T1203Exploitation for Client Execution

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Reported exploitation

Technologies

Your stack

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Your stack

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