Apple macOS up to 11.2.3 WebKit Storage use after free

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
7.9	$0-$5k	0.00

Summaryinfo

A vulnerability has been found in Apple macOS up to 11.2.3 and classified as critical. This vulnerability affects unknown code of the component WebKit Storage. The manipulation leads to use after free. This vulnerability is listed as CVE-2021-30661. The attack may be initiated remotely. In addition, an exploit is available. The affected component should be upgraded.

Detailsinfo

A vulnerability was found in Apple macOS up to 11.2.3 (Operating System). It has been rated as critical. This issue affects an unknown part of the component WebKit Storage. The manipulation with an unknown input leads to a use after free vulnerability. Using CWE to declare the problem leads to CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

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..

The weakness was presented 04/26/2021 by yangkang as HT212325 as confirmed advisory (Website). It is possible to read the advisory at support.apple.com. The identification of this vulnerability is CVE-2021-30661. It demands that the victim is doing some kind of user interaction. Technical details are unknown but a private exploit is available. The advisory points out:

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.

It is declared as attacked. The vulnerability scanner Nessus provides a plugin with the ID 223935 (Linux Distros Unpatched Vulnerability : CVE-2021-30661), which helps to determine the existence of the flaw in a target environment. The CISA Known Exploited Vulnerabilities Catalog lists this issue since 11/03/2021 with a due date of 11/17/2021:

Apply updates per vendor instructions.

Upgrading to version 11.3 eliminates this vulnerability. A possible mitigation has been published immediately after the disclosure of the vulnerability. The advisory contains the following remark:

A use after free issue was addressed with improved memory management.

The vulnerability is also documented in the databases at Zero-Day.cz (624), Tenable (223935) and EUVD (EUVD-2021-17578). Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Type

Operating System

Vendor

Apple

Name

macOS

Version

License

commercial

Website

Vendor: https://www.apple.com/

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 8.0
VulDB Meta Temp Score: 7.9

VulDB Base Score: 6.3
VulDB Temp Score: 6.0
VulDB Vector: 🔍
VulDB Reliability: 🔍

NVD Base Score: 8.8
NVD Vector: 🔍

CNA Base Score: 8.8
CNA Vector: 🔍

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
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Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
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VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

NVD Base Score: 🔍

Exploitinginfo

Class: Use after free
CWE: CWE-416 / CWE-119
CAPEC: 🔍
ATT&CK: 🔍

Physical: No
Local: No
Remote: Yes

Availability: 🔍
Access: Private
Status: Attacked

EPSS Score: 🔍
EPSS Percentile: 🔍

KEV Added: 🔍
KEV Due: 🔍
KEV Remediation: 🔍
KEV Ransomware: 🔍
KEV Notice: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Nessus ID: 223935
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2021-30661

Zero-Day.cz: 🔍

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

Reaction Time: 🔍
0-Day Time: 🔍
Exposure Time: 🔍

Upgrade: macOS 11.3

Timelineinfo

04/13/2021 🔍
04/26/2021 +13 days 🔍
04/26/2021 +0 days 🔍
04/27/2021 +1 days 🔍
07/29/2025 +1554 days 🔍

Sourcesinfo

Vendor: apple.com

Advisory: HT212325
Researcher: yangkang
Status: Confirmed

CVE: CVE-2021-30661 (🔍)
GCVE (CVE): GCVE-0-2021-30661
GCVE (VulDB): GCVE-100-174023
EUVD: 🔍
scip Labs: https://www.scip.ch/en/?labs.20180712

Entryinfo

Created: 04/27/2021 09:52
Updated: 07/29/2025 05:53
Changes: 04/27/2021 09:52 (19), 04/27/2021 09:55 (30), 05/01/2021 08:21 (1), 04/21/2024 14:57 (23), 05/15/2024 17:15 (2), 06/29/2024 02:49 (2), 09/14/2024 00:06 (1), 01/30/2025 02:34 (29), 03/05/2025 11:00 (2), 05/03/2025 21:58 (3), 07/29/2025 05:53 (1)
Complete: 🔍
Cache ID: 216::103