CVE-2025-43359 is a critical logic vulnerability identified in Apple’s UDP server socket implementation across multiple operating systems including macOS (Sonoma 14.8, Sequoia 15.7, Tahoe 26), iOS, iPadOS, tvOS, watchOS, and visionOS. The flaw arises from improper state management where a UDP server socket that is intended to bind exclusively to a local network interface may inadvertently bind to all available network interfaces on the device. This unintended binding expands the attack surface by exposing services to external networks that should have been restricted to local interfaces only. The vulnerability is categorized under CWE-670 (Improper Resource Shutdown or Release), indicating a failure in managing socket states correctly. With a CVSS v3.1 score of 9.8 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H), the vulnerability allows remote attackers to exploit the flaw without any authentication or user interaction, potentially leading to full compromise of confidentiality, integrity, and availability of affected systems. The issue was addressed by Apple through improved state management in the latest OS releases, but affected versions prior to these patches remain vulnerable. No known exploits have been reported in the wild as of now, but the criticality and ease of exploitation make it a high priority for patching.

For European organizations, the impact of CVE-2025-43359 can be severe. The unintended exposure of UDP services beyond local interfaces can lead to unauthorized access, data interception, or injection of malicious traffic, compromising sensitive information and disrupting critical services. This is particularly concerning for sectors such as finance, healthcare, government, and telecommunications, where Apple devices and macOS are widely used. The vulnerability’s ability to affect confidentiality, integrity, and availability simultaneously means that attackers could exfiltrate data, manipulate communications, or cause denial of service conditions. Given the lack of required authentication and user interaction, exploitation could be automated and widespread if attackers develop exploits. The exposure risk is amplified in environments with poor network segmentation or where UDP services handle sensitive or critical functions. Additionally, organizations relying on Apple’s ecosystem for IoT or operational technology may face increased risks due to expanded attack surfaces.

European organizations should prioritize immediate deployment of the security updates released by Apple for all affected operating systems including macOS Sonoma 14.8, Sequoia 15.7, Tahoe 26, iOS 18.7, iPadOS 18.7, tvOS 26, watchOS 26, and visionOS 26. Beyond patching, network administrators should audit UDP service configurations to ensure that sockets are explicitly bound to intended interfaces and implement strict network segmentation to limit exposure of critical services. Employing host-based firewalls to restrict inbound UDP traffic to trusted sources can reduce risk. Monitoring network traffic for unusual UDP activity or unexpected interface bindings can help detect exploitation attempts. Organizations should also review and harden any custom applications or services that rely on UDP sockets to ensure proper interface binding and state management. Finally, integrating this vulnerability into incident response plans and threat hunting activities will enhance preparedness against potential exploitation.