CVE-2026-39875: Apple macOS Privilege Escalation Flaw

CVE-2026-39875 Overview

CVE-2026-39875 is a local privilege escalation vulnerability in Apple macOS caused by a permissions issue. A malicious application running with low privileges on an affected system can exploit improper access control [CWE-276] to gain root privileges. Apple addressed the flaw by adding additional restrictions to the permission checks.

The vulnerability affects multiple macOS release trains and requires local access with low privileges. No user interaction is needed for exploitation, which increases the risk when attackers already have code execution on the endpoint.

Critical Impact
A malicious app running locally can escalate to root, giving attackers full control over the affected macOS system, including access to protected files, kernel extensions, and system configuration.

Affected Products

Apple macOS Sequoia prior to 15.7.8
Apple macOS Sonoma prior to 14.8.8
Apple macOS Tahoe prior to 26.6

Discovery Timeline

2026-07-27 - CVE-2026-39875 published to NVD
2026-07-29 - Last updated in NVD database

Technical Details for CVE-2026-39875

Vulnerability Analysis

CVE-2026-39875 stems from an incorrect default permissions issue [CWE-276] within a macOS system component. A local attacker with the ability to execute a malicious application can abuse the misconfigured permissions to elevate to the root user. Once root is obtained, the attacker can bypass System Integrity Protection boundaries at higher tiers, tamper with security tooling, and persist across reboots.

Apple's advisories describe the fix as adding additional restrictions to the permission model, indicating that a system resource or interface previously exposed operations to lower-privileged callers that should have been gated. This is a classic local elevation of privilege pattern on Apple platforms.

Root Cause

The root cause is improper permission enforcement on a macOS resource or interface. The affected component granted access rights broader than intended, allowing an unprivileged process to invoke functionality reserved for privileged callers. Apple's patch tightens these checks so that only authorized principals can perform the sensitive operation.

Attack Vector

Exploitation requires local access with low privileges and no user interaction. Attack chains typically start with initial access through phishing, a malicious installer, or a compromised third-party application. The attacker then executes a payload that abuses the vulnerable component to obtain root, converting a limited foothold into full system compromise. See the Apple Support Document #128067 for vendor detail.

Detection Methods for CVE-2026-39875

Indicators of Compromise

Unexpected processes spawned with uid=0 from applications that normally run as a standard user.
New or modified files under /Library/LaunchDaemons/, /System/Library/, or other root-owned locations following execution of an untrusted application.
Unsigned or ad-hoc signed binaries executing privileged system calls immediately after user-level process launch.

Detection Strategies

Monitor for privilege transitions where a child process gains root while the parent process runs as a standard user.
Alert on modifications to protected system directories and launch item paths originating from user-space applications.
Baseline legitimate use of privileged macOS services and flag anomalous callers of those interfaces.

Monitoring Recommendations

Ingest Endpoint Security framework (ES_EVENT_*) telemetry into a centralized analytics platform to correlate process lineage with privilege changes.
Track installations of new kernel extensions, system extensions, and persistence artifacts on macOS endpoints.
Review authentication and sudo logs for anomalous root escalations that do not map to legitimate administrative activity.

How to Mitigate CVE-2026-39875

Immediate Actions Required

Update affected endpoints to macOS Sequoia 15.7.8, macOS Sonoma 14.8.8, or macOS Tahoe 26.6 without delay.
Inventory macOS systems in the environment and prioritize patching devices used by administrators, developers, and privileged users.
Restrict installation of unsigned or unverified third-party applications through MDM policy and Gatekeeper configuration.

Patch Information

Apple released fixes in macOS Sequoia 15.7.8, macOS Sonoma 14.8.8, and macOS Tahoe 26.6. Refer to Apple Support Document #128067, Apple Support Document #128071, and Apple Support Document #128072 for the full advisory content and download instructions.

Workarounds

No vendor-provided workaround exists; applying the security update is the required remediation.
Enforce least-privilege on macOS user accounts and disable local administrator rights where not required.
Deploy application allowlisting via MDM to prevent execution of untrusted binaries that could carry an exploit payload.

bash

# Verify macOS build version and confirm patch level
sw_vers

# Trigger a software update check and install available updates
sudo softwareupdate --list
sudo softwareupdate --install --all --restart