CVE-2025-31240 is a vulnerability in the Apple Filing Protocol (AFP) implementation within macOS that allows an attacker to cause a system termination (crash or forced reboot) by mounting a specially crafted AFP network share. The root cause lies in insufficient input validation (CWE-20) when processing AFP share data, which can lead to unexpected system behavior and termination. The vulnerability is remotely exploitable without any authentication or user interaction, as an attacker only needs to present a malicious AFP share to a vulnerable macOS client attempting to mount it. This results in a denial-of-service (DoS) condition by impacting system availability. The issue affects multiple macOS versions prior to Ventura 13.7.6, Sequoia 15.5, and Sonoma 14.7.6, where Apple implemented improved checks to mitigate the flaw. The CVSS v3.1 base score is 7.5 (high), reflecting the network attack vector, low complexity, no privileges required, no user interaction, and impact limited to availability. No known active exploits have been reported, but the vulnerability poses a risk especially in environments where AFP shares are used or exposed to potentially hostile networks. The vulnerability highlights the risks of legacy protocols like AFP in modern network environments and the importance of robust input validation in network service implementations.

For European organizations, the primary impact of CVE-2025-31240 is denial of service on macOS systems that mount AFP network shares. This can disrupt business operations, especially in sectors relying on macOS workstations or servers for file sharing and collaboration. Organizations using AFP in mixed OS environments or legacy setups may experience system crashes, leading to productivity loss and potential downtime. While confidentiality and integrity are not directly affected, availability loss can impact critical workflows. The risk is higher for organizations with macOS devices exposed to untrusted or public networks where malicious AFP shares could be presented. Industries such as creative media, design, education, and research, which often use macOS extensively, may be particularly vulnerable. Additionally, organizations with remote or hybrid workforces using VPNs or remote access to internal AFP shares should be cautious. The lack of known exploits reduces immediate risk, but the ease of exploitation and network exposure make timely patching essential to prevent potential attacks.

1. Immediately apply the security updates provided by Apple: macOS Ventura 13.7.6, Sequoia 15.5, and Sonoma 14.7.6 or later versions. 2. Restrict AFP share access to trusted internal networks only; avoid exposing AFP services to the internet or untrusted networks. 3. Where possible, transition from AFP to more secure and modern file sharing protocols such as SMB or NFS, which have stronger security controls and are actively maintained. 4. Implement network segmentation and firewall rules to limit AFP traffic to authorized devices and users. 5. Monitor network traffic for unusual AFP share mounting attempts or anomalies that could indicate exploitation attempts. 6. Educate IT staff and users about the risks of mounting unknown or untrusted AFP shares. 7. Regularly audit macOS systems for compliance with patch levels and network access policies related to AFP. 8. Consider disabling AFP client functionality on macOS devices if not required to reduce attack surface.