Apple · iOS, iPadOS, and macOS
CVE-2021-30858
Apple iOS, iPadOS, macOS Use-After-Free Vulnerability
What it is
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.
CISA: 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.
What to do
Apply updates per vendor instructions.
Deadline for US federal agencies: November 17, 2021
- Added to the CISA list
- November 3, 2021
- Published
- August 24, 2021
- Severity
- High 8.8 CVSS 3.1
- Chance of attacks in the next 30 days (EPSS)
- 13% in the top 3.6% of all known vulnerabilities
- Weakness
- CWE-416
- More details
- NVD · CVE.org · CISA
All references (18)
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/BO6DMTHZR57J…
- https://www.debian.org/security/2021/dsa-4975
- https://www.debian.org/security/2021/dsa-4976
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/XYNV7ASK4LQV…
- https://support.apple.com/en-us/HT212804
- https://support.apple.com/en-us/HT212807
- http://seclists.org/fulldisclosure/2021/Sep/27
- http://seclists.org/fulldisclosure/2021/Sep/25
- http://seclists.org/fulldisclosure/2021/Sep/29
- http://www.openwall.com/lists/oss-security/2021/09/20/1
- http://seclists.org/fulldisclosure/2021/Sep/38
- http://seclists.org/fulldisclosure/2021/Sep/39
- https://support.apple.com/kb/HT212824
- http://seclists.org/fulldisclosure/2021/Sep/50
- http://www.openwall.com/lists/oss-security/2021/10/26/9
- http://www.openwall.com/lists/oss-security/2021/10/27/1
- http://www.openwall.com/lists/oss-security/2021/10/27/2
- http://www.openwall.com/lists/oss-security/2021/10/27/4
More exploited flaws from Apple
| Added | Vulnerability | Product | Severity | Attack chance |
|---|---|---|---|---|
| Aug 21, 2025 | Out-of-Bounds Write | iOS, iPadOS, and macOS | Critical 10.0 | 65% |
| Sep 11, 2023 | ImageIO Buffer Overflow | iOS, iPadOS, and macOS | High 7.8 | 53% |
| Apr 10, 2023 | IOSurfaceAccelerator Out-of-Bounds Write | iOS, iPadOS, and macOS | High 8.6 | 23% |
| Mar 30, 2023 | Out-of-Bounds Write | iOS, iPadOS, and macOS | High 7.8 | 5.2% |
| Sep 14, 2022 | Remote Code Execution | iOS, iPadOS, and macOS | High 7.8 | 5.6% |
| Sep 8, 2022 | Input Validation | iOS, iPadOS, and macOS | Medium 5.5 | 3.2% |
| Feb 11, 2022 | Webkit Use-After-Free | iOS, iPadOS, and macOS | High 8.8 | 16% |
| Nov 3, 2021 | WebKit Remote Code Execution | iOS, iPadOS, and macOS | Critical 9.8 | 7.7% |
Sources: Known Exploited Vulnerabilities (CISA, public domain), CVE records (cve.org) and EPSS (FIRST). The chance of attacks is the EPSS estimate that someone will try to exploit the flaw in the next 30 days.