CVE-2021-30858VulnerabilityPublished 11/03/2021Updated 10/24/2026

CVE-2021-30858: Apple iOS, iPadOS, macOS Use-After-Free Vulnerability

Affects Apple iOS, iPadOS, and macOSSource CISA KEV

Severity

High

No CVSS score published yet

Exploitation: Actively exploited – in CISA KEV since 11/03/2021
KEV deadline: 11/17/2021
EPSS: 13.4% chance of exploitation in 30 days – higher than 96% of CVEs

What to do

CISA required action

Apply updates per vendor instructions.

nvd.nist.gov/vuln/detail/CVE-2021-30858 (opens in a new tab)

Description

CVE-2021-30858 is a use-after-free vulnerability in Apple iOS, iPadOS, and macOS WebKit that allows code execution when processing malicious web content. It affects HTML parsers using WebKit, including Apple Safari and other products relying on WebKit. The vulnerability has been exploited in the wild.

Summary

Apple's WebKit engine in iOS, iPadOS, and macOS contains a use-after-free vulnerability (CWE-416) that can be triggered by maliciously crafted web content. This flaw enables remote code execution by exploiting memory management errors during HTML parsing. The vulnerability impacts Apple Safari and potentially other browsers or applications using WebKit for HTML processing. It has been observed in active exploitation scenarios.

Impact

Successful exploitation can lead to arbitrary code execution on affected devices, potentially allowing attackers to run malicious code with the privileges of the targeted application. This can compromise device security and user data.

Mitigation

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Users and administrators should monitor Apple security updates and apply any official fixes once available. Until then, exercise caution when visiting untrusted websites.

Weaknesses

CWE-416Use After Free (opens in a new tab)

What to do

Description

AnalysisAI-generated, updated 10/24/2026, 09:41:40 UTC

Weaknesses

References

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