Software Engineering Institute

Overview

iOS, iPadOS, tvOS, watchOS, and macOS contain a double-free vulnerability in the GNU kernel's lio_listio() function, which can allow a malicious application to achieve unsandboxed, kernel-level code execution.

Description

iOS, iPadOS, tvOS, watchOS, and macOS contain an a double-free vulnerability in the GNU kernel's lio_listio() function. This can lead to triggering a use-after-free condition. This vulnerability can allow code execution with kernel privileges. This vulnerability is being used by the public unc0ver 5.0 jailbreak utility, which claims to support all devices from iOS 11 through 13.5, excluding versions 12.3-12.3.2 and 12.4.2-12.4.5. It is also reported that this jailbreak works on modern iOS devices that use a CPU that supports Pointer Authentication Code (PAC), which indicates that PAC does not prevent exploitation of this vulnerability.

Impact

By convincing a user to run a malicious application on a device running iOS, iPadOS, tvOS, watchOS, or macOS, an attacker may be able to achieve arbitrary code execution in the kernel that is not restricted by sandboxes or other OS protections.

Solution

Apply updates

This issue is addressed in the following OS updates from Apple:
macOS Catalina 10.15.5 Supplemental Update, Security Update 2020-003 High Sierra
tvOS 13.4.6
watchOS 6.2.6
iOS 13.5.1 and iPadOS 13.5.1

Acknowledgements

This document was written by Will Dormann.

Vendor Information

References

• https://support.apple.com/en-us/HT211214
• https://support.apple.com/en-us/HT211215
• https://support.apple.com/en-us/HT211216
• https://support.apple.com/en-us/HT211217
• https://unc0ver.dev/
• https://googleprojectzero.blogspot.com/2020/07/how-to-unc0ver-0-day-in-4-hours-or-less.html
• https://googleprojectzero.blogspot.com/2019/02/examining-pointer-authentication-on.html