CVE-2024-45539 is an out-of-bounds write vulnerability identified in the CGI components of Synology DiskStation Manager (DSM) prior to versions 7.2.1-69057-2 and 7.2.2-72806, as well as Synology Unified Controller (DSMUC) before 3.1.4-23079. The vulnerability stems from improper bounds checking during processing of certain CGI requests, which allows an unauthenticated remote attacker to write data beyond the intended memory buffer. This memory corruption can cause the affected service to crash, resulting in a denial-of-service (DoS) condition. The CVSS v3.1 base score is 7.5, reflecting high severity due to network attack vector, no required privileges or user interaction, and a significant impact on availability. The vulnerability does not affect confidentiality or integrity directly. Although no public exploits are known at this time, the ease of exploitation and the critical role of DSM in managing Synology NAS devices make this a serious concern. The affected products are widely used in enterprise and SMB environments for data storage, backup, and unified device management. The vulnerability could disrupt business operations by causing NAS devices to become unresponsive or reboot unexpectedly. The flaw is present in specific DSM versions widely deployed before the patches were released. The vulnerability was reserved on 2024-09-02 and published on 2025-12-04, indicating a recent disclosure. No patches or exploit details are included in the provided data, so organizations must monitor Synology advisories closely. The vulnerability’s root cause is a classic out-of-bounds write in CGI modules, a common web-facing attack surface in NAS management interfaces.

For European organizations, the primary impact is denial of service on Synology NAS devices running vulnerable DSM versions. This can lead to unavailability of critical data storage, backup services, and unified device management functions, disrupting business continuity. Industries relying heavily on NAS for file sharing, archival, or virtualization storage—such as finance, healthcare, manufacturing, and public sector—may experience operational downtime. The lack of confidentiality or integrity impact reduces risk of data breach but does not eliminate operational risk. The vulnerability’s network accessibility and no authentication requirement increase the attack surface, potentially allowing remote attackers to disrupt services without insider access. Given the widespread use of Synology products in Europe, especially in SMBs and some enterprise environments, the risk of targeted or opportunistic DoS attacks is significant. Organizations with NAS devices exposed to the internet or poorly segmented internal networks are particularly vulnerable. The absence of known exploits in the wild currently lowers immediate risk but does not preclude future exploitation. The impact is compounded in environments lacking robust monitoring or incident response capabilities.

Organizations should immediately identify all Synology NAS devices and Unified Controllers running affected DSM versions (prior to 7.2.1-69057-2 and 7.2.2-72806 for DSM, and prior to 3.1.4-23079 for DSMUC). They must apply the official patches or upgrade to the fixed versions as soon as they become available from Synology. Until patches are applied, restrict network access to management interfaces by implementing firewall rules that limit access to trusted IP addresses and internal networks only. Disable or restrict CGI services if possible, or apply web application firewall (WAF) rules to detect and block suspicious CGI requests that could trigger out-of-bounds writes. Monitor NAS device logs and network traffic for unusual crashes or restarts indicative of exploitation attempts. Conduct vulnerability scanning and penetration testing focused on DSM CGI components to identify exposure. Establish incident response plans for NAS service outages and ensure backups are current and tested for recovery. Engage with Synology support for guidance and stay updated on advisories. For critical environments, consider network segmentation and isolation of NAS devices to reduce exposure.