CVE-2021-30661Known exploitationNetwork attack vector

Arbitrary code execution via WebKit Storage use-after-free

Published Sep 8, 2021 · Updated Oct 21, 2025

Use-after-free in Apple WebKit Storage allows remote attackers to execute arbitrary code through maliciously crafted web content. The component accesses memory after it has been freed while processing attacker-controlled content; Apple has not disclosed the specific object or code path. Exploitation requires the content to be processed in an affected WebKit context, and Apple reported active exploitation.

CVSS severity8.8
High
EPSS probability4.49%
Next 30 days · Sep 16, 2026
Known exploitationReported
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in Apple WebKit Storage allows remote attackers to execute arbitrary code through maliciously crafted web content. The component accesses memory after it has been freed while processing attacker-controlled content; Apple has not disclosed the specific object or code path. Exploitation requires the content to be processed in an affected WebKit context, and Apple reported active exploitation.

The record

CVE
CVE-2021-30661
Published
Sep 8, 2021
Updated
Oct 21, 2025
Vendor
Apple
Product
iOS and iPadOS
Classifications
CWE-416, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 8, 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 <14.5

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Apple · iOS and iPadOSversion=unspecified <14.5
Apple · Safariversion=unspecified <14.1
Apple · tvOSversion=unspecified <14.5
Apple · macOSversion=unspecified <11.3; version=unspecified <12.5
Apple · watchOSversion=unspecified <7.4

Published CVSS scores

8.8CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
8.8NIST NVDCVSS: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

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

CWE-416Use After Free
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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