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Known Exploited Vulnerability
8.8
HIGH CVSS 3.1
CVE-2021-30661
Apple Multiple Products WebKit Storage Use-After-Free Vulnerability - [Actively Exploited]
Description

A use after free issue was addressed with improved memory management. This issue is fixed in Safari 14.1, iOS 12.5.3, iOS 14.5 and iPadOS 14.5, watchOS 7.4, tvOS 14.5, macOS Big Sur 11.3. Processing maliciously crafted web content may lead to arbitrary code execution. Apple is aware of a report that this issue may have been actively exploited..

INFO

Published Date :

Sept. 8, 2021, 3:15 p.m.

Last Modified :

Oct. 23, 2025, 2:53 p.m.

Remotely Exploit :

Yes !

Source :

[email protected]
CISA Notification
CISA KEV (Known Exploited Vulnerabilities)

For the benefit of the cybersecurity community and network defenders—and to help every organization better manage vulnerabilities and keep pace with threat activity—CISA maintains the authoritative source of vulnerabilities that have been exploited in the wild.

Description :

Apple iOS, iPadOS, macOS, tvOS, watchOS, and Safari WebKit Storage contain a use-after-free vulnerability that leads to code execution when processing maliciously crafted web content. This vulnerability could impact HTML parsers that use WebKit, including but not limited to Apple Safari and non-Apple products which rely on WebKit for HTML processing.

Required Action :

Apply updates per vendor instructions.

Notes :

https://nvd.nist.gov/vuln/detail/CVE-2021-30661

Affected Products

The following products are affected by CVE-2021-30661 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID Vendor Product Action
1 Apple macos
2 Apple iphone_os
3 Apple tvos
4 Apple watchos
5 Apple safari
6 Apple ipados
: Total Affected Vendor : 1 | Products : 6
CVSS Scores
The Common Vulnerability Scoring System is a standardized framework for assessing the severity of vulnerabilities in software and systems. We collect and displays CVSS scores from various sources for each CVE.
Score Version Severity Vector Exploitability Score Impact Score Source
CVSS 2.0 MEDIUM [email protected]
CVSS 3.1 HIGH [email protected]
CVSS 3.1 HIGH 134c704f-9b21-4f2e-91b3-4a467353bcc0
Solution
This addresses a WebKit use-after-free vulnerability that may allow arbitrary code execution.
  • Update Safari, iOS, iPadOS, watchOS, tvOS, and macOS.
  • Upgrade to the latest available versions of affected packages.
Public PoC/Exploit Available at Github

CVE-2021-30661 has a 1 public PoC/Exploit available at Github. Go to the Public Exploits tab to see the list.

References to Advisories, Solutions, and Tools

Here, you will find a curated list of external links that provide in-depth information, practical solutions, and valuable tools related to CVE-2021-30661.

URL Resource
https://support.apple.com/en-us/HT212317 Vendor Advisory
https://support.apple.com/en-us/HT212318 Vendor Advisory
https://support.apple.com/en-us/HT212323 Vendor Advisory
https://support.apple.com/en-us/HT212324 Vendor Advisory
https://support.apple.com/en-us/HT212325 Vendor Advisory
https://support.apple.com/en-us/HT212341 Vendor Advisory
https://support.apple.com/en-us/HT212317 Vendor Advisory
https://support.apple.com/en-us/HT212318 Vendor Advisory
https://support.apple.com/en-us/HT212323 Vendor Advisory
https://support.apple.com/en-us/HT212324 Vendor Advisory
https://support.apple.com/en-us/HT212325 Vendor Advisory
https://support.apple.com/en-us/HT212341 Vendor Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-30661 Third Party Advisory US Government Resource
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2021-30661 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2021-30661 weaknesses.

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

Profile Photo
Ostorlab/KEV

Ostorlab KEV: One-command to detect most remotely known exploitable vulnerabilities. Sourced from CISA KEV, Google's Tsunami, Ostorlab's Asteroid and Bug Bounty programs.

cisa-kev vulnerability 0day cisa exploits

Updated: 3 weeks ago
588 stars 42 fork 42 watcher
Born at : April 19, 2022, 8:58 a.m. This repo has been linked 1290 different CVEs too.

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2021-30661 vulnerability anywhere in the article.

Results are limited to the first 20 news articles due to potential performance issues.

The following table lists the changes that have been made to the CVE-2021-30661 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

  • Modified Analysis by [email protected]

    Oct. 23, 2025

    Action Type Old Value New Value
    Added Reference Type CISA-ADP: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-30661 Types: Third Party Advisory, US Government Resource
  • CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0

    Oct. 22, 2025

    Action Type Old Value New Value
    Added Reference https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-30661
  • CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0

    Oct. 21, 2025

    Action Type Old Value New Value
    Removed Reference https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-30661
  • CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0

    Oct. 21, 2025

    Action Type Old Value New Value
    Added Reference https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-30661
  • Modified Analysis by [email protected]

    Feb. 28, 2025

    Action Type Old Value New Value
  • CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0

    Jan. 29, 2025

    Action Type Old Value New Value
    Added CVSS V3.1 AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
    Added CWE CWE-416
  • CVE Modified by af854a3a-2127-422b-91ae-364da2661108

    Nov. 21, 2024

    Action Type Old Value New Value
    Added Reference https://support.apple.com/en-us/HT212317
    Added Reference https://support.apple.com/en-us/HT212318
    Added Reference https://support.apple.com/en-us/HT212323
    Added Reference https://support.apple.com/en-us/HT212324
    Added Reference https://support.apple.com/en-us/HT212325
    Added Reference https://support.apple.com/en-us/HT212341
  • CVE CISA KEV Update by 9119a7d8-5eab-497f-8521-727c672e3725

    May. 16, 2024

    Action Type Old Value New Value
    Changed Vulnerability Name Apple Multiple Products Use-After-Free Vulnerability Apple Multiple Products WebKit Storage Use-After-Free Vulnerability
  • CVE Modified by [email protected]

    May. 14, 2024

    Action Type Old Value New Value
  • Reanalysis by [email protected]

    Sep. 20, 2021

    Action Type Old Value New Value
  • Initial Analysis by [email protected]

    Sep. 17, 2021

    Action Type Old Value New Value
    Added CVSS V2 Metadata Victim must voluntarily interact with attack mechanism
    Added CVSS V2 NIST (AV:N/AC:M/Au:N/C:P/I:P/A:P)
    Added CVSS V3.1 NIST AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
    Changed Reference Type https://support.apple.com/en-us/HT212317 No Types Assigned https://support.apple.com/en-us/HT212317 Vendor Advisory
    Changed Reference Type https://support.apple.com/en-us/HT212318 No Types Assigned https://support.apple.com/en-us/HT212318 Vendor Advisory
    Changed Reference Type https://support.apple.com/en-us/HT212323 No Types Assigned https://support.apple.com/en-us/HT212323 Vendor Advisory
    Changed Reference Type https://support.apple.com/en-us/HT212324 No Types Assigned https://support.apple.com/en-us/HT212324 Vendor Advisory
    Changed Reference Type https://support.apple.com/en-us/HT212325 No Types Assigned https://support.apple.com/en-us/HT212325 Vendor Advisory
    Changed Reference Type https://support.apple.com/en-us/HT212341 No Types Assigned https://support.apple.com/en-us/HT212341 Vendor Advisory
    Added CWE NIST CWE-416
    Added CPE Configuration OR *cpe:2.3:a:apple:safari:*:*:*:*:*:*:*:* versions up to (excluding) 14.1 *cpe:2.3:o:apple:ipados:*:*:*:*:*:*:*:* versions up to (excluding) 14.5 *cpe:2.3:o:apple:iphone_os:*:*:*:*:*:*:*:* versions up to (excluding) 12.5.3 *cpe:2.3:o:apple:iphone_os:*:*:*:*:*:*:*:* versions from (including) 14.0 up to (excluding) 14.5 *cpe:2.3:o:apple:macos:*:*:*:*:*:*:*:* versions from (including) 11.0 up to (excluding) 11.3 *cpe:2.3:o:apple:tvos:*:*:*:*:*:*:*:* versions up to (excluding) 14.5 *cpe:2.3:o:apple:watchos:*:*:*:*:*:*:*:* versions up to (excluding) 7.4
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.
Vulnerability Scoring Details
Base CVSS Score: 8.8
Attack Vector
Attack Complexity
Privileges Required
User Interaction
Scope
Confidentiality Impact
Integrity Impact
Availability Impact
Base CVSS Score: 6.8
Access Vector
Access Complexity
Authentication
Confidentiality Impact
Integrity Impact
Availability Impact
Exploit Prediction

EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days.

0.10 }} -0.14%

score

0.29011

percentile