CVE-2026-86894: Apple macOS Privilege Escalation Vulnerability

CVE-2026-86894 Overview

CVE-2026-86894 is a sandbox escape vulnerability in Apple macOS resolved in macOS Golden Gate 27. Apple describes the root cause as a logic issue addressed with improved checks. An application running inside the macOS sandbox can leverage the flaw to break out of its confinement and gain access to resources outside the sandbox boundary.

The issue is tracked under CWE-693: Protection Mechanism Failure. Apple published mitigation guidance in Apple Security Update 149035.

Critical Impact
A malicious or compromised app can escape the macOS sandbox, bypassing a core protection mechanism designed to contain untrusted code and limit its access to user data and system resources.

Affected Products

Apple macOS versions prior to macOS Golden Gate 27
Systems running unpatched macOS with sandboxed third-party applications
Any macOS deployment relying on App Sandbox for containment of untrusted code

Discovery Timeline

2026-09-14 - CVE-2026-86894 published to the National Vulnerability Database
2026-09-16 - Entry last modified in the NVD

Technical Details for CVE-2026-86894

Vulnerability Analysis

CVE-2026-86894 is a protection mechanism failure in the macOS App Sandbox. The sandbox enforces mandatory access control policies that restrict which files, IPC endpoints, and system services an application can reach. Apple's advisory attributes the flaw to a logic issue in these checks, meaning the enforcement code reached an incorrect decision under specific conditions rather than failing at a memory-safety boundary.

The practical result is a confinement bypass. An application that the operating system believes is restricted can perform operations reserved for unsandboxed processes. This weakens the defense-in-depth model that macOS uses to contain browser tabs, document viewers, App Store applications, and other components that process untrusted input.

Apple resolved the vulnerability in macOS Golden Gate 27 by adding improved checks to the affected logic path. The advisory does not name a reporter or publish reproduction details.

Root Cause

The root cause is a logic error in the sandbox enforcement path. A condition that should have blocked or restricted an action instead permitted it. Apple's fix adds additional validation to close the gap, consistent with the [CWE-693] classification.

Attack Vector

Exploitation requires code execution inside a sandboxed process on the target macOS system. Delivery vectors include a malicious App Store or notarized application, a compromised sandboxed helper, or exploitation of a separate bug in a sandboxed component such as a browser renderer. Once the attacker controls the sandboxed process, the logic flaw is triggered to reach resources outside the sandbox boundary.

No public proof-of-concept, exploit code, or CISA KEV listing is associated with this CVE at the time of writing. Apple has not published technical reproduction details.

Detection Methods for CVE-2026-86894

Indicators of Compromise

Sandboxed applications spawning child processes or accessing file paths outside their declared container
Unexpected writes to user home directories, /Library, or other locations that a sandboxed app should not reach
macOS sandboxd or kernel log entries showing denied operations immediately followed by successful equivalents from the same process

Detection Strategies

Monitor process lineage for sandboxed parent processes performing operations inconsistent with their entitlements
Correlate file, network, and IPC telemetry against each application's expected sandbox profile
Flag sandboxed processes that access Mach services, XPC endpoints, or Keychain items not listed in their entitlements

Monitoring Recommendations

Ingest Endpoint Security framework (ES_EVENT_*) telemetry from managed macOS endpoints into a centralized analytics pipeline
Track macOS build versions across the fleet to identify hosts still running versions prior to macOS Golden Gate 27
Alert on new or unsigned binaries executed by sandboxed applications, particularly browsers and document processors

How to Mitigate CVE-2026-86894

Immediate Actions Required

Upgrade affected macOS systems to macOS Golden Gate 27, which contains the vendor fix
Inventory endpoints that cannot be upgraded immediately and prioritize them based on exposure to untrusted content
Review installed third-party applications and remove any that are unnecessary or from untrusted publishers

Patch Information

Apple addressed CVE-2026-86894 in macOS Golden Gate 27 by improving the logic checks in the affected sandbox code path. Details are published in Apple Security Update 149035. Administrators should deploy the update through Software Update, Mobile Device Management (MDM), or Apple Business Manager.

Workarounds

No vendor-supplied workaround is documented; applying the macOS Golden Gate 27 update is the supported remediation
Reduce exposure by limiting installation of sandboxed applications that process untrusted input from the internet
Enforce Gatekeeper and notarization requirements, and restrict application installation to approved sources via MDM policy

bash

# Verify installed macOS version on an endpoint
sw_vers -productVersion

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