CVE-2025-43539: Apple macOS Buffer Overflow Vulnerability

CVE-2025-43539 Overview

CVE-2025-43539 is a memory corruption vulnerability affecting multiple Apple operating systems, including macOS, iOS, iPadOS, tvOS, watchOS, and visionOS. The vulnerability stems from improper bounds checking during file processing operations. When a user processes a specially crafted malicious file, the application fails to properly validate input boundaries, leading to memory corruption that could be exploited by attackers.

This vulnerability requires user interaction, meaning an attacker must convince a victim to open or process a malicious file. However, once triggered, the memory corruption can potentially allow attackers to execute arbitrary code, access sensitive information, or cause application crashes on affected systems.

Critical Impact

Processing a maliciously crafted file can lead to memory corruption, potentially enabling arbitrary code execution or unauthorized data access across Apple's ecosystem of devices.

Affected Products

• iOS 18.7.3 and iPadOS 18.7.3 (and earlier versions)
• iOS 26.2 and iPadOS 26.2 (and earlier versions)
• macOS Sequoia 15.7.3 (and earlier versions)
• macOS Sonoma 14.8.3 (and earlier versions)
• macOS Tahoe 26.2 (and earlier versions)
• tvOS 26.2 (and earlier versions)
• visionOS 26.2 (and earlier versions)
• watchOS 26.2 (and earlier versions)

Discovery Timeline

• 2025-12-12 - CVE-2025-43539 published to NVD
• 2026-04-02 - Last updated in NVD database

Technical Details for CVE-2025-43539

Vulnerability Analysis

This vulnerability is classified under CWE-787 (Out-of-Bounds Write) and CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer). The flaw occurs when processing files that contain malformed or unexpected data structures, causing the application to write data beyond allocated memory boundaries.

Out-of-bounds write vulnerabilities are particularly dangerous because they can corrupt adjacent memory regions, potentially overwriting critical data structures, function pointers, or security mechanisms. In the context of Apple's operating systems, successful exploitation could bypass security protections and gain elevated privileges.

The network attack vector indicates that malicious files can be delivered remotely via email attachments, downloads, or other network-based delivery mechanisms, broadening the potential attack surface significantly.

Root Cause

The root cause of CVE-2025-43539 lies in insufficient bounds checking within Apple's file processing routines. When parsing file structures, the affected code fails to properly validate that data lengths and offsets remain within expected boundaries. This allows specially crafted files to specify dimensions or offsets that exceed allocated buffer sizes, resulting in writes to unintended memory locations.

Apple addressed this vulnerability by implementing improved bounds checks that properly validate all input parameters before memory operations are performed, ensuring that write operations cannot exceed allocated buffer boundaries.

Attack Vector

The attack vector for this vulnerability requires user interaction but can be initiated remotely. An attacker would need to:

1. Create a specially crafted malicious file designed to trigger the bounds checking flaw
2. Deliver the file to the victim via email, messaging, web download, or other file transfer mechanisms
3. Convince the victim to open or process the malicious file on an affected Apple device

Once the victim interacts with the malicious file, the memory corruption occurs automatically during processing. The vulnerability affects multiple file types depending on the specific component that lacks proper bounds validation.

Due to the nature of the vulnerability and Apple's security practices, detailed technical exploitation information has not been publicly disclosed. Security researchers should refer to the Apple Security Advisory #125887 and Apple Security Advisory #125888 for additional technical context.

Detection Methods for CVE-2025-43539

Indicators of Compromise

• Unexpected application crashes when opening files, particularly with crash logs indicating memory access violations
• System logs showing segmentation faults or memory corruption errors in file processing services
• Presence of suspicious or malformed files with unusual file structures or embedded data
• Anomalous memory allocation patterns in system monitoring tools

Detection Strategies

• Deploy endpoint detection and response (EDR) solutions capable of monitoring memory access patterns and detecting out-of-bounds operations
• Implement file integrity monitoring to detect suspicious files before they are processed by users
• Configure application-level logging to capture detailed information about file processing operations and failures
• Use behavioral analysis tools to detect anomalous application behavior during file operations

Monitoring Recommendations

• Monitor crash reports and system logs for memory corruption indicators on Apple devices
• Implement centralized logging for all Apple endpoints to correlate potential exploitation attempts
• Enable Apple's built-in security features including XProtect and Gatekeeper for additional protection layers
• Configure alerts for unusual file processing activity or repeated application crashes

How to Mitigate CVE-2025-43539

Immediate Actions Required

• Update all affected Apple devices to the latest patched versions immediately
• Educate users about the risks of opening files from untrusted sources
• Implement email and web filtering to scan attachments and downloads for suspicious content
• Review and restrict file sharing permissions in enterprise environments

Patch Information

Apple has released security updates addressing this vulnerability across all affected platforms. Organizations and users should immediately update to the following versions or later:

• iOS/iPadOS: Update to iOS 18.7.3, iPadOS 18.7.3, iOS 26.2, or iPadOS 26.2
• macOS Sequoia: Update to version 15.7.3 or later
• macOS Sonoma: Update to version 14.8.3 or later
• macOS Tahoe: Update to version 26.2 or later
• tvOS: Update to version 26.2 or later
• visionOS: Update to version 26.2 or later
• watchOS: Update to version 26.2 or later

Detailed patch information is available in the official Apple Security Advisories:

• Apple Security Advisory #125887
• Apple Security Advisory #125888

Workarounds

• Enable Gatekeeper and ensure it is set to allow apps only from the App Store or identified developers
• Disable automatic file preview features in email clients and file browsers where possible
• Implement network-level controls to inspect and quarantine suspicious file attachments
• Use sandboxed environments or virtual machines when working with files from untrusted sources

# Verify macOS Gatekeeper status
spctl --status

# Enable Gatekeeper if disabled
sudo spctl --master-enable

# Check for available software updates
softwareupdate --list

# Install all available updates
sudo softwareupdate --install --all