Apple iOS/iPadOS up to 15.1.1 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	$5k-$25k	0.00

Summaryinfo

A vulnerability was found in Apple iOS and iPadOS up to 15.1.1. It has been classified as problematic. This impacts an unknown function of the component Kernel. Performing a manipulation results in buffer overflow. This vulnerability is identified as CVE-2021-30993. The attack can be initiated remotely. There is not any exploit available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability, which was classified as problematic, was found in Apple iOS and iPadOS up to 15.1.1 (Smartphone Operating System). This affects an unknown code block 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 released 12/13/2021 by OSS-Fuzz and Ned Williamson as HT212976 as confirmed advisory (Website). It is possible to read the advisory at support.apple.com. This vulnerability is uniquely identified as CVE-2021-30993. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 03/08/2026). It is expected to see the exploit prices for this product increasing in the near future. The advisory points out:

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

Upgrading to version 15.2 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). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Affected

Apple macOS

Productinfo

Type

Smartphone Operating System

Vendor

Apple

Name

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: 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
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
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Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
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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: iOS/iPadOS 15.2

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: HT212976
Researcher: OSS-Fuzz, Ned Williamson
Status: Confirmed

CVE: CVE-2021-30993 (🔍)
GCVE (CVE): GCVE-0-2021-30993
GCVE (VulDB): GCVE-100-188571
CERT Bund: WID-SEC-2026-0631 - Apple macOS: Mehrere Schwachstellen

scip Labs: https://www.scip.ch/en/?labs.20150917

Entryinfo

Created: 12/17/2021 16:44
Updated: 03/08/2026 12:51
Changes: 12/17/2021 16:44 (2), 12/17/2021 16:45 (17), 12/17/2021 16:48 (28), 12/23/2021 09:57 (1), 03/08/2026 12:51 (21)
Complete: 🔍
Cache ID: 216::103

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