CVEs / CVE-2021-30858

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

Known exploited in the CISA KEV catalog since 3 Nov 2021
high 8.8 CVSS 3.1 (NVD)
EPSS 13.3% chance of exploitation in the next 30 days, higher than 96% of CVEs (30 Oct 2026)
Last changed at its sources 17 Jun 2026

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Summary

Apple iOS, iPadOS, and macOS WebKit contain a use-after-free 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.
CISA, Known Exploited Vulnerabilities catalog

Description

A use after free issue was addressed with improved memory management. This issue is fixed in iOS 14.8 and iPadOS 14.8, macOS Big Sur 11.6. 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.
The CVE record, via NVD · published 24 Aug 2021 · NVD status: Analyzed

Affected and fixed versions

As stated by the CVE record (from the CNA)
Product	Affected	Fixed in
Apple macOS	from unspecified, before 11.6	11.6
Apple iOS	from unspecified, before 14.8	14.8

Exploitation

In CISA KEV since	3 Nov 2021
Due date for US federal agencies	17 Nov 2021
Used in ransomware campaigns	Unknown
Required action	Apply updates per vendor instructions.

Severity

CVSS 3.1	8.8 high `CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H` Scored by NVD
Weakness	CWE-416

References

CVE-2021-30858 on NVD
CVE-2021-30858 in the CISA KEV catalog
CVE-2021-30858 on OSV
http://seclists.org/fulldisclosure/2021/Sep/25 Mailing List, Third Party Advisory
http://seclists.org/fulldisclosure/2021/Sep/27 Mailing List, Third Party Advisory
http://seclists.org/fulldisclosure/2021/Sep/29 Mailing List, Third Party Advisory
http://seclists.org/fulldisclosure/2021/Sep/38 Mailing List, Third Party Advisory
http://seclists.org/fulldisclosure/2021/Sep/39 Mailing List, Third Party Advisory
http://seclists.org/fulldisclosure/2021/Sep/50 Mailing List, Third Party Advisory
http://www.openwall.com/lists/oss-security/2021/09/20/1 Mailing List
http://www.openwall.com/lists/oss-security/2021/10/26/9 Mailing List
http://www.openwall.com/lists/oss-security/2021/10/27/1 Mailing List
http://www.openwall.com/lists/oss-security/2021/10/27/2 Mailing List
http://www.openwall.com/lists/oss-security/2021/10/27/4 Mailing List
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/BO6DMTHZR57JDBOXPSNR2MKDMCRWV265/ Release Notes
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/XYNV7ASK4LQVAUMJXNXBS3Z7RVDQ2N3W/ Release Notes
https://support.apple.com/en-us/HT212804 Third Party Advisory
https://support.apple.com/en-us/HT212807 Third Party Advisory
https://support.apple.com/kb/HT212824 Third Party Advisory
https://www.debian.org/security/2021/dsa-4975 Mailing List, Third Party Advisory
https://www.debian.org/security/2021/dsa-4976 Mailing List, Third Party Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-30858 US Government Resource

Sources

Exploitation status from the CISA Known Exploited Vulnerabilities catalog. EPSS scores from FIRST. Descriptions, severity and references from the National Vulnerability Database. Open-source package versions from OSV (CC-BY 4.0). Text is shown as each source states it; Stackurity does not edit it. Check the vendor's advisory before acting.

This product uses data from the NVD API but is not endorsed or certified by the NVD.