CVE-2025-43521
📋 TL;DR
A code-signing downgrade vulnerability in Intel-based Mac computers allows malicious apps to bypass security restrictions and access sensitive user data. This affects macOS systems before specific security updates. Users with unpatched Intel-based Macs are vulnerable to potential data exposure.
💻 Affected Systems
- macOS
📦 What is this software?
Macos by Apple
macOS is Apple's desktop and laptop operating system powering Mac computers used by millions of professionals, developers, creative professionals, and enterprise users worldwide. Built on a Unix foundation with the Darwin kernel and modern Cocoa frameworks, macOS delivers a seamless ecosystem integr...
Learn more about Macos →⚠️ Risk & Real-World Impact
Worst Case
Malicious app gains unauthorized access to sensitive user data including passwords, financial information, or personal documents through bypassed code-signing restrictions.
Likely Case
Malware or compromised legitimate apps could access user data they shouldn't normally be able to reach, potentially leading to data theft or privacy violations.
If Mitigated
With proper patching and app security controls, the vulnerability is eliminated through enhanced code-signing enforcement.
🎯 Exploit Status
Requires user to install or run a malicious application. The downgrade attack bypasses code-signing restrictions that normally prevent unauthorized data access.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: macOS Tahoe 26.2, macOS Sequoia 15.7.3
Vendor Advisory: https://support.apple.com/en-us/125886
Restart Required: Yes
Instructions:
1. Open System Settings 2. Click General 3. Click Software Update 4. Install available updates 5. Restart when prompted
🔧 Temporary Workarounds
Restrict App Installation Sources
allOnly allow apps from the App Store and identified developers in System Settings
Enable Full Disk Access Restrictions
allReview and restrict app permissions in System Settings > Privacy & Security
🧯 If You Can't Patch
- Implement application allowlisting to control which apps can run
- Use endpoint detection and response (EDR) tools to monitor for suspicious app behavior
🔍 How to Verify
Check if Vulnerable:
Check macOS version in System Settings > General > About. If version is earlier than Tahoe 26.2 or Sequoia 15.7.3 and using Intel processor, system is vulnerable.Check Version:
sw_versVerify Fix Applied:
Verify macOS version shows Tahoe 26.2 or Sequoia 15.7.3 or later in System Settings > General > About.📡 Detection & Monitoring
Log Indicators:
- Unusual app access to protected directories
- Code-signing validation failures in system logs
Network Indicators:
- Unexpected outbound connections from newly installed apps
SIEM Query:
source="macos_system_logs" AND (event="code_signature" OR event="app_access") AND result="failure"