CVE-2021-30952Known exploitationPublic exploitNetwork attack vector

Code execution via WebKit integer overflow

Published Aug 24, 2021 · Updated Mar 6, 2026

Integer overflow in WebKit on affected Apple operating systems allows remote attackers to execute arbitrary code via crafted web content. Apple has not disclosed the affected WebKit function or integer operation; it states that improved input validation corrects the overflow. The initial exploit grants read/write access in the WebContent process; broader device compromise requires additional exploit-chain stages.

CVSS severity8.8
High
EPSS probability6.96%
Next 30 days · Sep 16, 2026
Known exploitationReported
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Integer overflow in WebKit on affected Apple operating systems allows remote attackers to execute arbitrary code via crafted web content. Apple has not disclosed the affected WebKit function or integer operation; it states that improved input validation corrects the overflow. The initial exploit grants read/write access in the WebContent process; broader device compromise requires additional exploit-chain stages.

The record

CVE
CVE-2021-30952
Published
Aug 24, 2021
Updated
Mar 6, 2026
Vendor
Apple
Product
iOS and iPadOS
Classifications
CWE-190, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 24, 2021CVE publishedPublication date reported by the CVE source.
  2. Mar 5, 2026Exploitation reportedCISA Known Exploited Vulnerabilities Catalog entry
  3. Mar 6, 2026Record 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 <15.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Apple · iOS and iPadOSversion=unspecified <15.2
Apple · macOSversion=unspecified <12.1; version=unspecified <15.2
Apple · watchOSversion=unspecified <8.3

Published CVSS scores

8.8CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
6.8NIST NVDAV:N/AC:M/Au:N/C:P/I:P/A:P
7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:N/UI:R/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.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationReported
Public exploitPublished

Weakness, pattern, technique

CWE-190Integer Overflow or Wraparound
T1203Exploitation for Client Execution

Public exploit references

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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