CVE-2025-43526
📋 TL;DR
A URL validation vulnerability in macOS and Safari allows web content opened via file URLs to bypass Lockdown Mode restrictions and access Web APIs that should be blocked. This affects macOS users with Lockdown Mode enabled who open malicious local files. The high CVSS score reflects the potential for significant security bypass.
💻 Affected Systems
- macOS
- Safari
📦 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 →Safari by Apple
⚠️ Risk & Real-World Impact
Worst Case
An attacker could execute arbitrary code, steal sensitive data, or perform unauthorized actions by tricking a user into opening a malicious local HTML file while Lockdown Mode is enabled.
Likely Case
An attacker could bypass Lockdown Mode's security restrictions to access device sensors, location data, or other Web APIs that should be blocked, leading to privacy violations.
If Mitigated
With Lockdown Mode disabled or proper patching, the vulnerability is neutralized, maintaining intended security boundaries.
🎯 Exploit Status
Exploitation requires user interaction (opening a malicious file) and Lockdown Mode enabled. No public exploit details are available.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: macOS Tahoe 26.2, Safari 26.2
Vendor Advisory: https://support.apple.com/en-us/125886
Restart Required: Yes
Instructions:
1. Open System Settings on macOS. 2. Go to General > Software Update. 3. Install macOS Tahoe 26.2 update. 4. For Safari, update via App Store or as part of macOS update. 5. Restart the system after installation.
🔧 Temporary Workarounds
Disable Lockdown Mode
macOSTemporarily turn off Lockdown Mode to prevent exploitation until patched.
Open System Settings > Privacy & Security > Lockdown Mode, toggle off
Avoid Opening Local HTML Files
allDo not open HTML files from untrusted sources while Lockdown Mode is enabled.
🧯 If You Can't Patch
- Keep Lockdown Mode disabled until patching is possible.
- Implement application allowlisting to block execution of untrusted HTML files.
🔍 How to Verify
Check if Vulnerable:
Check macOS version in System Settings > General > About. If below Tahoe 26.2 and Lockdown Mode is enabled, the system is vulnerable.Check Version:
sw_vers for macOS, defaults read /Applications/Safari.app/Contents/Info.plist CFBundleShortVersionString for SafariVerify Fix Applied:
Confirm macOS version is Tahoe 26.2 or later and Safari is 26.2 or later in System Settings or Safari > About Safari.📡 Detection & Monitoring
Log Indicators:
- Unusual file URL accesses in Safari or system logs, especially with Lockdown Mode enabled
Network Indicators:
- Unexpected outbound connections from Safari after opening local files
SIEM Query:
source="*safari*" AND event="file_url_access" AND lockdown_mode="enabled"