Apple macOS up to 12.0 Kernel buffer overflow

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.
5.4	$0-$5k	0.00

Summaryinfo

A vulnerability was found in Apple macOS up to 12.0. It has been declared as problematic. Affected by this vulnerability is an unknown functionality of the component Kernel. The manipulation results in buffer overflow. This vulnerability was named CVE-2021-30993. The attack may be performed from remote. There is no available exploit. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability was found in Apple macOS up to 12.0 (Operating System). It has been classified as problematic. Affected is some unknown processing of the component Kernel. The manipulation with an unknown input leads to a buffer overflow vulnerability. CWE is classifying the issue as CWE-120. The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer, leading to a buffer overflow. This is going to have an impact on confidentiality, integrity, and availability.

The weakness was presented 12/13/2021 by OSS-Fuzz and Ned Williamson as HT212978 as confirmed advisory (Website). The advisory is shared for download at support.apple.com. This vulnerability is traded as CVE-2021-30993. There are neither technical details nor an exploit publicly available. The advisory points out:

An attacker in a privileged network position may be able to execute arbitrary code

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 buffer overflow issue was addressed with improved memory handling.

The vulnerability is also documented in the vulnerability database at CERT Bund (WID-SEC-2026-0631). Once again VulDB remains the best source 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: 5.6
VulDB Meta Temp Score: 5.4

VulDB Base Score: 5.6
VulDB Temp Score: 5.4
VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

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: Buffer overflow
CWE: CWE-120 / CWE-119
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: OSS-Fuzz, Ned Williamson
Status: Confirmed

CVE: CVE-2021-30993 (🔍)
GCVE (CVE): GCVE-0-2021-30993
GCVE (VulDB): GCVE-100-188628
CERT Bund: WID-SEC-2026-0631 - Apple macOS: Mehrere Schwachstellen

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

Entryinfo

Created: 12/17/2021 21:16
Updated: 03/08/2026 12:51
Changes: 12/17/2021 21:16 (19), 12/17/2021 21:19 (28), 12/23/2021 15:26 (1), 03/08/2026 12:51 (21)
Complete: 🔍
Cache ID: 216::103