CVE Watch—

CVE-2021-30666

Apple iOS WebKit Buffer Overflow Vulnerability

CVSS

—

No CVSS

EPSS

3.0%

p87

KEV

YES

Nov 3, 2021

Exploit Today

0-100

Published: — · Last modified: —

EPSS · 30d

3.0%EPSS · 30 days3.0%

2026-09-172026-10-15

KEV catalog record

Product

Apple / iOS

Vulnerability

Apple iOS WebKit Buffer Overflow Vulnerability

Added to KEV

Nov 3, 2021

Remediate by

Nov 17, 2021

Known ransomware use

Summary description

Apple iOS WebKit contains a buffer-overflow vulnerability that leads to code execution when processing maliciously crafted web content. This vulnerability could impact HTML parsers that use WebKit, including but not limited to Apple Safari and non-Apple products which rely on WebKit for HTML processing.

Required action

Apply updates per vendor instructions.

Notes

https://nvd.nist.gov/vuln/detail/CVE-2021-30666

Related CVEs

CVECVSSEPSSKEVRExploitTitleMod.

CVE-2016-4657—

99.3%

KEV—80Apple iOS Webkit Memory Corruption Vulnerability—CVE-2016-4655—

98.4%

KEV—80Apple iOS Information Disclosure Vulnerability—CVE-2016-4656—

97.8%

KEV—79Apple iOS Memory Corruption Vulnerability—CVE-2021-30762—

95.9%

KEV—79Apple iOS WebKit Use-After-Free Vulnerability—CVE-2021-30761—

95.7%

KEV—79Apple iOS WebKit Memory Corruption Vulnerability—CVE-2022-42856—

95.0%

KEV—78Apple iOS Type Confusion Vulnerability—