CVE-2025-43257: macOS Sequoia Sandbox Escape Vulnerability

CVE-2025-43257 Overview

CVE-2025-43257 is a symlink handling vulnerability in macOS Sequoia that allows a malicious application to break out of its sandbox. The vulnerability stems from improper handling of symbolic links (symlinks), enabling applications to escape the security restrictions imposed by the macOS sandbox environment and potentially access system resources or user data that should be inaccessible.

Critical Impact

A malicious application can exploit improper symlink handling to escape sandbox restrictions, potentially gaining unauthorized access to sensitive system resources and user data outside its designated containment boundary.

Affected Products

• macOS Sequoia versions prior to 15.6

Discovery Timeline

• 2026-04-02 - CVE CVE-2025-43257 published to NVD
• 2026-04-02 - Last updated in NVD database

Technical Details for CVE-2025-43257

Vulnerability Analysis

This vulnerability is classified under CWE-59 (Improper Link Resolution Before File Access), commonly known as a symlink attack or symbolic link following vulnerability. The flaw exists in how macOS handles symbolic links within the context of sandboxed applications.

When a sandboxed application creates or interacts with symbolic links, the operating system must properly validate that the link's target falls within the application's permitted access boundaries. In this case, macOS Sequoia failed to adequately verify symlink targets before allowing file operations, creating a path traversal condition that could be exploited to access resources outside the sandbox.

The vulnerability requires local access and low privileges to exploit, with the attack vector being local execution of a malicious application. Successfully exploiting this vulnerability allows an attacker to bypass sandbox isolation, potentially compromising the confidentiality and integrity of data on the affected system.

Root Cause

The root cause of CVE-2025-43257 lies in insufficient validation of symbolic link resolution paths within the macOS sandbox enforcement mechanism. When resolving symlinks, the system failed to properly check whether the final resolved path remained within the boundaries permitted by the sandbox profile. This allowed carefully crafted symlinks to point to locations outside the sandbox container, effectively bypassing the intended security isolation.

Attack Vector

The attack vector for this vulnerability is local, requiring an attacker to either install a malicious application on the target system or compromise an existing sandboxed application. The exploitation flow involves:

1. A malicious or compromised sandboxed application creates a symbolic link within its sandbox directory
2. The symlink is crafted to point to a sensitive location outside the sandbox (e.g., user documents, system files, or other application data)
3. When the application accesses the symlink, the improper validation allows the operation to follow the link to the forbidden location
4. The attacker gains read or write access to resources that should be protected by sandbox restrictions

The attack does not require user interaction beyond initially running the malicious application, and the scope is changed as the vulnerability allows access to resources outside the vulnerable component's security authority.

Detection Methods for CVE-2025-43257

Indicators of Compromise

• Unusual symlink creation patterns within sandboxed application containers
• Applications accessing files outside their designated sandbox directories
• Unexpected file access events in protected system locations from sandboxed processes
• Anomalous sandbox violation logs that do not result in blocked operations

Detection Strategies

• Monitor for symlink creation events within application sandbox containers using fs_usage or endpoint security framework
• Implement file integrity monitoring on sensitive directories to detect unauthorized access
• Review system logs for sandbox-related events in /var/log/system.log and Unified Logging
• Deploy endpoint detection solutions capable of monitoring file system operations and symlink resolution

Monitoring Recommendations

• Enable enhanced file system auditing on sensitive directories and system resources
• Configure alerts for sandboxed applications performing file operations outside their expected scope
• Monitor for applications exhibiting unusual behavior patterns such as excessive symlink creation
• Review macOS Endpoint Security Framework telemetry for sandbox boundary violations

How to Mitigate CVE-2025-43257

Immediate Actions Required

• Update macOS Sequoia to version 15.6 or later immediately
• Review installed applications for any suspicious or untrusted software
• Audit third-party applications for unusual behavior or file access patterns
• Consider temporarily restricting installation of new applications until patching is complete

Patch Information

Apple has addressed this vulnerability in macOS Sequoia 15.6 with improved handling of symlinks. The fix ensures proper validation of symbolic link targets before allowing file operations, preventing symlinks from resolving to locations outside the sandbox boundary.

Users should update their systems through System Preferences > Software Update or by downloading the update from Apple Support Article.

Workarounds

• Limit installation and execution of applications to only those from trusted sources (Mac App Store or identified developers)
• Review and restrict application permissions through System Preferences > Security & Privacy
• Consider implementing additional file access monitoring tools until the patch can be applied
• Remove or disable any suspicious third-party applications until the update is installed

# Check current macOS version
sw_vers -productVersion

# Verify macOS is updated to 15.6 or later
# If version is below 15.6, update immediately via:
# System Preferences > Software Update

# List installed applications for review
ls -la /Applications/