CVE-2021-30666Apple iOS WebKit Buffer Overflow Vulnerability

A buffer overflow issue was addressed with improved memory handling. This issue is fixed in iOS 12.5.3. Processing maliciously crafted web content may lead to arbitrary code execution. Apple is aware of a report that this issue may have been actively exploited..

8.8 HIGHEPSS 2.99%⚡ Known Exploited (CISA KEV)NVD: Analyzed

Last updated: 2026-06-17 03:50 UTC

OverviewCVSS details

8.8HIGHCVSS 3.1

Score source: NVD
NVD status: Analyzed
Published: Sep 8, 2021
Assigner: apple

Affected

iOS (Apple)

Versions: before 12.5
Fixed in: 12.5

Exploitation

Public exploit: None listed
CISA KEV: Listed · Nov 3, 2021
KEV due date: Nov 17, 2021
Ransomware use: Unknown
SSVC: Exploitation active · Automatable no · Impact total

EPSS · FIRST, scored Nov 7

2.99%chance of exploitation in 30 days

Higher than 87.43% of CVEs

CVSS 3.1 · NVD

8.8High

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Attack vector: Network
Attack complexity: Low
Privileges required: None
User interaction: Required
Scope: Unchanged
Confidentiality impact: High
Integrity impact: High
Availability impact: High

CVSS 2.0 · NVD

6.8Medium

AV:N/AC:M/Au:N/C:P/I:P/A:P

Attack vector: Network
Attack complexity: Medium
Authentication: None
Confidentiality impact: Partial
Integrity impact: Partial
Availability impact: Partial

NVD status: Analyzed

Overview Affected Products References

NVD CVE.org

Overview

Severity

Score	Severity	Version	Vector String
8.8	HIGH	3.1NVD	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
6.8	MEDIUM	2.0NVD	AV:N/AC:M/Au:N/C:P/I:P/A:P

CISA required action

⚡ Known exploited · remediation due Nov 17, 2021

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Details

CVE ID: CVE-2021-30666
Status: Analyzed
Assigner (CNA): apple
Published: Sep 8, 2021
Last modified: 2026-06-17 03:50 UTC
Weaknesses: CWE-119

Sources

Refreshed hourly from the sources above. Last fetched 2026-11-08 10:39 UTC.