CVE-2024-38440 is a heap-based buffer overflow vulnerability identified in Netatalk, an open-source implementation of the Apple Filing Protocol (AFP) used primarily on Unix-like systems for file sharing. The vulnerability stems from an off-by-one error in the FPLoginExt operation, specifically within the BN_bin2bn function call in the uams_dhx_pam.c source file. The root cause is the lack of proper validation of the length field after parsing user-supplied data, which leads to writing a null byte out-of-bounds on the heap. This single-byte overflow can corrupt adjacent heap metadata, potentially triggering a segmentation fault and causing the AFP daemon (afpd) to crash. The issue affects Netatalk versions prior to 3.2.1, with fixed versions including 2.4.1 and 3.1.19. The vulnerability does not require any privileges or user interaction to exploit, as it can be triggered remotely by sending crafted AFP login extension requests. While the primary impact is denial of service, the heap corruption could theoretically be leveraged for more severe attacks, though no such exploits are currently known. The CVSS v3.1 base score of 7.5 reflects a high severity due to network attack vector, low attack complexity, no privileges required, no user interaction, and impact limited to availability. The vulnerability is tracked under CWE-193 (Off-by-one Error).

For European organizations, the primary impact of CVE-2024-38440 is the potential disruption of AFP file sharing services due to denial of service caused by the heap overflow and subsequent segmentation fault. Organizations relying on Netatalk for network-attached storage, legacy file sharing, or integration with Apple devices may experience service outages, affecting business continuity and productivity. Critical sectors such as government, finance, education, and healthcare that utilize Unix-based file servers could face operational interruptions. Although no known remote code execution exploits exist yet, the heap corruption could be a stepping stone for more advanced attacks if combined with other vulnerabilities. The vulnerability's network accessibility and lack of authentication requirements increase the risk of exploitation by remote attackers. Given the widespread use of Unix/Linux systems in Europe and the presence of legacy AFP services, the threat is relevant, especially in environments where patching cycles are slow or where Netatalk is embedded in specialized appliances.

The most effective mitigation is to upgrade Netatalk to version 3.2.1 or later, or apply patches backported in versions 2.4.1 and 3.1.19. Organizations should audit their environments to identify all Netatalk instances, including embedded systems and NAS devices that may use it. If immediate patching is not feasible, administrators can temporarily disable AFP services or restrict network access to the AFP port (548) using firewalls or network segmentation to limit exposure. Monitoring AFP daemon logs for crashes or unusual activity can help detect exploitation attempts. Additionally, applying heap hardening and memory protection techniques (e.g., ASLR, heap canaries) at the OS level can reduce the risk of successful exploitation. Regular vulnerability scanning and penetration testing targeting AFP services should be incorporated into security programs. Finally, organizations should maintain an inventory of legacy protocols in use and plan migration to more secure file sharing alternatives where possible.