Apple macOS up to 12.0 WebKit race condition

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.
6.0	$0-$5k	0.00

Summaryinfo

A vulnerability, which was classified as critical, has been found in Apple macOS up to 12.0. Affected by this issue is some unknown functionality of the component WebKit. The manipulation leads to race condition. This vulnerability is documented as CVE-2021-30984. The attack can be initiated remotely. There is not any exploit available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as critical, has been found in Apple macOS up to 12.0 (Operating System). This issue affects an unknown functionality of the component WebKit. The manipulation with an unknown input leads to a race condition vulnerability. Using CWE to declare the problem leads to CWE-362. The product contains a code sequence that can run concurrently with other code, and the code sequence requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence that is operating concurrently. Impacted is confidentiality, integrity, and availability.

The weakness was released 12/13/2021 by Kunlun Lab as HT212978 as confirmed advisory (Website). It is possible to read the advisory at support.apple.com. The identification of this vulnerability is CVE-2021-30984. It demands that the victim is doing some kind of user interaction. The technical details are unknown and an exploit is not publicly available. The advisory points out:

Processing maliciously crafted web content may lead to arbitrary code execution

Upgrading to version 12.1 eliminates this vulnerability. A possible mitigation has been published immediately after the disclosure of the vulnerability. The advisory contains the following remark:

A race condition was addressed with improved state handling.

The vulnerability is also documented in the vulnerability database at CERT Bund (WID-SEC-2026-0631). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Affected

Apple macOS

Productinfo

Type

Operating System

Vendor

Apple

Name

macOS

Version

12.0

License

commercial

Website

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

CPE 2.3info

🔍

CPE 2.2info

🔍

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.3
VulDB Meta Temp Score: 6.0

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

CVSSv2info

AV	AC	Au	C	I	A
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💳	💳	💳	💳	💳	💳
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Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock

VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

Exploitinginfo

Class: Race condition
CWE: CWE-362
CAPEC: 🔍
ATT&CK: 🔍

Physical: No
Local: No
Remote: Yes

Availability: 🔍
Status: Not defined

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

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

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

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

Upgrade: macOS 12.1

Timelineinfo

04/13/2021 🔍
12/13/2021 +244 days 🔍
12/13/2021 +0 days 🔍
12/17/2021 +4 days 🔍
03/08/2026 +1542 days 🔍

Sourcesinfo

Vendor: apple.com

Advisory: HT212978
Researcher: Kunlun Lab
Status: Confirmed

CVE: CVE-2021-30984 (🔍)
GCVE (CVE): GCVE-0-2021-30984
GCVE (VulDB): GCVE-100-188651
CERT Bund: WID-SEC-2026-0631 - Apple macOS: Mehrere Schwachstellen

scip Labs: https://www.scip.ch/en/?labs.20180712

Entryinfo

Created: 12/17/2021 21:25
Updated: 03/08/2026 11:53
Changes: 12/17/2021 21:25 (19), 12/17/2021 21:28 (28), 12/24/2021 07:22 (1), 03/08/2026 11:53 (21)
Complete: 🔍
Cache ID: 216::103

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