Apple watchOS up to 7.4.1 WebKit 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.
6.0	$0-$5k	0.00

Summaryinfo

A vulnerability was found in Apple watchOS up to 7.4.1. It has been rated as critical. The affected element is an unknown function of the component WebKit. Performing a manipulation results in use after free. This vulnerability is known as CVE-2021-21779. Remote exploitation of the attack is possible. No exploit is available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability, which was classified as critical, was found in Apple watchOS up to 7.4.1 (Smartwatch Operating System). This affects an unknown function of the component WebKit. The manipulation with an unknown input leads to a use after free vulnerability. CWE is classifying the issue as CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. This is going to have an impact on confidentiality, integrity, and availability.

The weakness was published 05/24/2021 by Marcin Towalski as HT212533 as confirmed advisory (Website). The advisory is shared at support.apple.com. This vulnerability is uniquely identified as CVE-2021-21779. It demands that the victim is doing some kind of user interaction. Neither technical details nor an exploit are publicly available. The advisory points out:

Processing maliciously crafted web content may lead to arbitrary code execution

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.

Upgrading to version 7.5 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 vulnerability database at Tenable (241427). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Type

Smartwatch Operating System

Vendor

Apple

Name

watchOS

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: 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
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

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: Use after free
CWE: CWE-416 / 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

Nessus ID: 241427
Nessus Name: RHEL 7 : webkitgtk4 (RHSA-2025:10364)

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

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

Upgrade: watchOS 7.5

Timelineinfo

01/04/2021 🔍
05/24/2021 +139 days 🔍
05/24/2021 +0 days 🔍
05/25/2021 +1 days 🔍
07/10/2025 +1507 days 🔍

Sourcesinfo

Vendor: apple.com

Advisory: HT212533
Researcher: Marcin Towalski
Status: Confirmed

CVE: CVE-2021-21779 (🔍)
GCVE (CVE): GCVE-0-2021-21779
GCVE (VulDB): GCVE-100-175665

Entryinfo

Created: 05/25/2021 12:17
Updated: 07/10/2025 13:15
Changes: 05/25/2021 12:17 (19), 05/25/2021 12:20 (27), 05/28/2021 08:30 (4), 07/10/2025 13:15 (16)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.