CVE-2019-8526

What Is Affected?

This vulnerability affects macOS, Apple's desktop operating system, in a component reachable by a local, low-privileged process or user.

Overview

CVE-2019-8526 is a use-after-free vulnerability (CWE-416) in macOS that can be exploited by a local attacker with low privileges to escalate to higher privileges, without requiring any user interaction. It is rated high severity (CVSS 7.8).

Technical Details

A use-after-free bug occurs when a program continues to use a pointer to memory after that memory has been freed, allowing an attacker who can control what gets reallocated into that freed memory region to hijack the program's execution flow. In a privilege-escalation context, this typically lets a process running with limited rights execute code with the privileges of a more trusted component, such as the kernel or a system daemon.

Discovery

Apple documented and fixed this issue in a macOS security update, referenced in Apple support article HT209600.

Exploitation Context

CISA added this CVE to the KEV catalog in April 2023, confirming real-world exploitation. Local privilege-escalation bugs like this are commonly chained with an initial remote code-execution vulnerability (such as a browser or document-parsing bug) to achieve full system compromise from a single malicious file or web page.

Remediation

1. Update macOS to the latest supported version.
2. Apply the fix referenced in Apple support article HT209600 if running an affected legacy macOS release.
3. Limit local account privileges and avoid running routine tasks from administrator accounts.
4. Monitor for unexpected privilege escalation or unusual process behavior using endpoint detection tooling.
5. Keep all locally installed applications updated, since this class of bug is often paired with a separate remote-entry vulnerability.