Apple macOS up to 11.3.0 WebKit integer overflow

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7.9	$0-$5k	0.00

Summaryinfo

A vulnerability was found in Apple macOS up to 11.3.0. It has been classified as critical. Affected by this vulnerability is an unknown functionality of the component WebKit. The manipulation leads to integer overflow. This vulnerability is referenced as CVE-2021-30663. Remote exploitation of the attack is possible. Furthermore, an exploit is available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability was found in Apple macOS up to 11.3.0 (Operating System) and classified as critical. This issue affects an unknown code block of the component WebKit. The manipulation with an unknown input leads to a integer overflow vulnerability. Using CWE to declare the problem leads to CWE-190. The product performs a calculation that can produce an integer overflow or wraparound, when the logic assumes that the resulting value will always be larger than the original value. This can introduce other weaknesses when the calculation is used for resource management or execution control. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

An integer overflow was addressed with improved input validation. This issue is fixed in iOS 14.5.1 and iPadOS 14.5.1, tvOS 14.6, iOS 12.5.3, Safari 14.1.1, macOS Big Sur 11.3.1. Processing maliciously crafted web content may lead to arbitrary code execution.

The weakness was published 05/03/2021 as HT212335 as confirmed advisory (Website). It is possible to read the advisory at support.apple.com. The identification of this vulnerability is CVE-2021-30663. 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 241427 (RHEL 7 : webkitgtk4 (RHSA-2025:10364)), 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 11.3.1 eliminates this vulnerability. A possible mitigation has been published immediately after the disclosure of the vulnerability. The advisory contains the following remark:

An integer overflow was addressed with improved input validation.

The vulnerability is also documented in the databases at Zero-Day.cz (626), Tenable (241427) and EUVD (EUVD-2021-17580). Statistical analysis made it clear that VulDB provides the best quality 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
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VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

NVD Base Score: 🔍

Exploitinginfo

Class: Integer overflow
CWE: CWE-190 / CWE-189
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: 241427
Nessus Name: RHEL 7 : webkitgtk4 (RHSA-2025:10364)

Zero-Day.cz: 🔍

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

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

Upgrade: macOS 11.3.1

Timelineinfo

04/13/2021 🔍
05/03/2021 +20 days 🔍
05/03/2021 +0 days 🔍
05/06/2021 +3 days 🔍
07/29/2025 +1545 days 🔍

Sourcesinfo

Vendor: apple.com

Advisory: HT212335
Status: Confirmed

CVE: CVE-2021-30663 (🔍)
GCVE (CVE): GCVE-0-2021-30663
GCVE (VulDB): GCVE-100-174515
EUVD: 🔍
scip Labs: https://www.scip.ch/en/?labs.20180712

Entryinfo

Created: 05/06/2021 09:13
Updated: 07/29/2025 04:48
Changes: 05/06/2021 09:13 (1), 05/06/2021 09:14 (17), 05/06/2021 09:17 (30), 05/09/2021 07:23 (1), 04/21/2024 15:36 (23), 05/15/2024 17:15 (2), 06/28/2024 11:53 (2), 09/14/2024 00:06 (1), 02/03/2025 16:17 (29), 05/03/2025 21:08 (3), 07/10/2025 16:53 (2), 07/29/2025 04:48 (1)
Complete: 🔍
Cache ID: 216::103

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.