CVE-2026-28829: Apple macOS Privilege Escalation Flaw

CVE-2026-28829 Overview

A permissions issue has been identified in Apple macOS that could allow a malicious application to modify protected parts of the file system. This vulnerability stems from incorrect permission assignment for critical resources (CWE-732), where insufficient restrictions on file system access could enable unauthorized modifications to system-protected areas.

Critical Impact

An application with local access may bypass file system protections and modify protected areas, potentially compromising system integrity or enabling persistence mechanisms.

Affected Products

• macOS Sequoia versions prior to 15.7.5
• macOS Sonoma versions prior to 14.8.5
• macOS Tahoe versions prior to 26.4

Discovery Timeline

• 2026-03-25 - CVE-2026-28829 published to NVD
• 2026-03-25 - Last updated in NVD database

Technical Details for CVE-2026-28829

Vulnerability Analysis

This vulnerability is classified as CWE-732 (Incorrect Permission Assignment for Critical Resource), indicating that the affected macOS versions fail to properly enforce access restrictions on certain file system operations. The vulnerability requires local access and user interaction to exploit, meaning an attacker would need to deliver a malicious application to the target system and convince the user to execute it.

The impact is focused on integrity—successful exploitation allows modification of protected file system areas without affecting confidentiality or causing system availability issues. This could enable attackers to tamper with system configurations, install persistent malware components, or modify protected application bundles.

Root Cause

The underlying cause is insufficient permission validation when applications attempt to access or modify protected areas of the macOS file system. macOS employs System Integrity Protection (SIP) and other mechanisms to restrict access to critical system locations, but this vulnerability indicates a gap in those protections that allowed certain operations to bypass the intended restrictions.

Apple addressed this by implementing additional restrictions to strengthen the permission checks and prevent unauthorized file system modifications.

Attack Vector

The attack vector is local, requiring an attacker to deliver a malicious application to the target macOS system. The exploitation scenario involves:

1. Attacker crafts a malicious macOS application designed to exploit the permission weakness
2. User downloads and executes the application (user interaction required)
3. The application leverages the permission flaw to write to or modify protected file system locations
4. Attacker achieves persistence or modifies system behavior through the unauthorized changes

Since no public exploit code is available for this vulnerability, the specific technical mechanism used to bypass file system protections has not been publicly disclosed. Technical details may be found in Apple Security Advisory #126794, Apple Security Advisory #126795, and Apple Security Advisory #126796.

Detection Methods for CVE-2026-28829

Indicators of Compromise

• Unexpected modifications to files in protected system directories such as /System, /Library, or /usr
• Applications writing to locations typically protected by System Integrity Protection
• Suspicious file system activity from recently installed or unsigned applications
• Modified system configuration files or preference files without administrative action

Detection Strategies

• Monitor file system integrity for changes to protected system locations using tools like osquery or file integrity monitoring solutions
• Audit application behavior for attempts to access or modify protected paths
• Review system logs in Console.app for permission-related errors or warnings that indicate bypass attempts
• Implement endpoint detection rules to flag applications attempting to write to SIP-protected directories

Monitoring Recommendations

• Enable advanced audit logging on macOS systems to capture file system modification events
• Deploy endpoint detection and response (EDR) solutions capable of monitoring macOS file system activity
• Establish baseline file system state for critical system directories to detect unauthorized changes
• Configure alerts for any application attempting to modify /System, /Library/Preferences, or other protected paths

How to Mitigate CVE-2026-28829

Immediate Actions Required

• Update all affected macOS systems to the patched versions: macOS Sequoia 15.7.5, macOS Sonoma 14.8.5, or macOS Tahoe 26.4
• Verify System Integrity Protection (SIP) is enabled on all macOS endpoints
• Review recently installed applications and remove any untrusted or suspicious software
• Restrict application installations to the Mac App Store or identified developers through Gatekeeper settings

Patch Information

Apple has released security updates addressing this vulnerability:

Organizations should prioritize deployment of these updates through their standard patch management processes.

Workarounds

• Ensure System Integrity Protection (SIP) remains enabled—do not disable it for development or troubleshooting purposes
• Implement application allowlisting to prevent execution of untrusted applications
• Use macOS Gatekeeper configured to allow only apps from the App Store and identified developers
• Educate users about the risks of downloading and running applications from untrusted sources

# Verify System Integrity Protection status
csrutil status

# Check Gatekeeper settings
spctl --status

# View recent file system modifications in protected areas
sudo log show --predicate 'eventMessage contains "SIP"' --last 24h