CVE-2026-84584: Apple macOS Privilege Escalation Vulnerability

CVE-2026-84584 Overview

CVE-2026-84584 is a symlink handling vulnerability in Apple macOS that allows a sandboxed application to escape its sandbox restrictions. Apple resolved the issue in macOS Golden Gate 27 through improved symlink handling. The flaw is tracked under CWE-59: Improper Link Resolution Before File Access, commonly known as a symlink following weakness. Successful exploitation enables a local, low-privileged process to affect resources outside its assigned sandbox scope, breaking a core macOS security boundary.

Critical Impact
A malicious app running inside the macOS sandbox can leverage symlink resolution to access or modify files outside its container, undermining application isolation on affected macOS systems.

Affected Products

Apple macOS (versions prior to macOS Golden Gate 27)
Applications relying on macOS App Sandbox for isolation
Third-party software distributed through the Mac App Store subject to sandbox entitlements

Discovery Timeline

2026-09-14 - CVE-2026-84584 published to the National Vulnerability Database
2026-09-17 - Last updated in NVD database

Technical Details for CVE-2026-84584

Vulnerability Analysis

The vulnerability resides in how macOS resolves symbolic links during file operations initiated by sandboxed applications. When a sandboxed process references a path that traverses a symlink, the operating system fails to correctly re-evaluate the target against the sandbox policy. This allows the process to reach files and directories that should be blocked by the sandbox profile. The result is a sandbox escape that grants unauthorized read and write access to sensitive resources on the local system. Apple's advisory confirms the fix addresses the issue through improved handling of symlinks.

Root Cause

The root cause is improper link resolution before file access, categorized as CWE-59. The sandbox enforcement layer evaluates path permissions against the requested path rather than the fully canonicalized target of any intermediate symbolic links. An attacker-controlled symlink placed within a writable sandbox directory can therefore redirect subsequent file operations to arbitrary locations that the sandbox profile would otherwise deny.

Attack Vector

Exploitation requires local access and low-privileged code execution, typically achieved by convincing a user to install a malicious application from an untrusted source. The attacker crafts symbolic links within a sandbox-writable directory that point to targets outside the sandbox container. Follow-on file operations then dereference the symlinks and act on the redirected paths. No user interaction beyond initial execution of the malicious app is required, and the scope change permits impact on resources controlled by a different security authority. Refer to the Apple Support Article for vendor details.

Detection Methods for CVE-2026-84584

Indicators of Compromise

Creation of symbolic links inside sandbox container directories under ~/Library/Containers/ pointing to paths outside the container
File access events from sandboxed processes targeting resources outside their declared entitlements
Unexpected modifications to user data or system files immediately following execution of a recently installed application

Detection Strategies

Monitor symlink() and symlinkat() system calls originating from sandboxed processes and correlate targets against the process container path
Alert on file open operations where the canonicalized path differs from the requested path for processes with active sandbox profiles
Baseline expected file access patterns for App Store applications and flag deviations that cross container boundaries

Monitoring Recommendations

Enable Endpoint Security framework telemetry for ES_EVENT_TYPE_NOTIFY_LINK and ES_EVENT_TYPE_NOTIFY_OPEN events
Aggregate macOS Unified Log entries related to sandboxd denials and anomalies for forensic review
Track application installations from outside the Mac App Store and correlate with subsequent filesystem anomalies

How to Mitigate CVE-2026-84584

Immediate Actions Required

Upgrade all affected Macs to macOS Golden Gate 27 or later without delay
Audit installed applications and remove any that originate from untrusted developers or unknown sources
Verify sandbox-enforced applications continue to operate correctly after applying the update

Patch Information

Apple addressed CVE-2026-84584 in macOS Golden Gate 27 with improved symlink handling. Administrators should deploy the update through Software Update, mobile device management (MDM), or Apple Business Manager. Full details are available in the Apple Support Article.

Workarounds

Restrict installation of applications to signed, notarized software from the Mac App Store or verified developers via Gatekeeper policy
Enforce System Integrity Protection (SIP) and File System Protections to reduce the blast radius of a sandbox escape
Apply MDM configuration profiles that block execution of unsigned binaries until the patch is deployed fleet-wide

bash

# Verify the installed macOS version meets the patched release
sw_vers -productVersion

# Trigger a software update check from the command line
sudo softwareupdate --list
sudo softwareupdate --install --all --restart