CVE-2025-43401 is a vulnerability in Apple macOS that allows a remote attacker to cause a denial-of-service (DoS) condition by exploiting insufficient input validation. The issue was addressed by Apple through improved validation mechanisms in the latest security updates for macOS Sequoia 15.7.2, macOS Tahoe 26.1, and macOS Sonoma 14.8.2. The vulnerability is classified under CWE-20, which relates to improper input validation, indicating that the system fails to properly check or sanitize incoming data, leading to a state where it can be overwhelmed or crash. The CVSS v3.1 base score is 7.5, with vector metrics indicating that the attack can be launched remotely over the network (AV:N), requires no privileges (PR:N), no user interaction (UI:N), and affects system availability (A:H) without impacting confidentiality or integrity. This means an attacker can trigger the DoS condition without authentication or user involvement, making it a significant risk especially for publicly accessible macOS services or devices. Although no exploits have been observed in the wild yet, the vulnerability's characteristics make it a candidate for future exploitation. The lack of detailed affected versions suggests that multiple or all versions prior to the patched releases may be vulnerable. Organizations running macOS in critical roles should prioritize applying the patches to prevent potential service outages.

For European organizations, this vulnerability poses a risk of service disruption on macOS systems, which could affect business continuity, especially in environments where macOS devices are integral to operations such as creative industries, software development, and certain enterprise environments. The denial-of-service condition could be exploited remotely without authentication, potentially allowing attackers to disrupt services or workflows. While confidentiality and integrity are not impacted, availability degradation can lead to operational delays, loss of productivity, and potential reputational damage. Critical infrastructure or public-facing macOS services in sectors like finance, media, and government could be targeted to cause outages. The absence of known exploits in the wild currently reduces immediate risk but does not eliminate the threat, emphasizing the need for proactive patching. The impact is heightened in organizations with a high density of macOS endpoints or those that rely on macOS for critical functions.

European organizations should immediately verify their macOS versions and apply the security updates macOS Sequoia 15.7.2, Tahoe 26.1, or Sonoma 14.8.2 as applicable. Network-level protections such as firewalls and intrusion prevention systems should be configured to monitor and potentially block suspicious traffic targeting macOS devices. Organizations should implement network segmentation to isolate critical macOS systems from untrusted networks, reducing exposure. Continuous monitoring for unusual system crashes or service disruptions on macOS endpoints can help detect exploitation attempts early. Incident response plans should be updated to include procedures for handling macOS DoS incidents. Additionally, organizations should educate IT staff about this vulnerability and ensure that macOS devices are included in vulnerability management and patching cycles. Where possible, limit exposure of macOS services to the internet or untrusted networks until patches are applied. Finally, maintain backups and redundancy for critical macOS-dependent services to minimize downtime if a DoS occurs.