CVE-2024-39793 is a critical security vulnerability identified in the Wavlink AC3000 router firmware version M33A8.V5030.210505. The flaw resides in the nas.cgi set_nas() proftpd functionality, which handles network-attached storage (NAS) configuration via HTTP requests. Specifically, the vulnerability is an external control of system or configuration setting (CWE-15), where an attacker with valid authentication can craft HTTP POST requests targeting the ftp_name parameter to inject unauthorized configuration changes. This leads to a permission bypass, allowing the attacker to manipulate system settings beyond their intended privileges. The vulnerability affects confidentiality by potentially exposing sensitive data, integrity by allowing unauthorized configuration changes, and availability by possibly disrupting NAS or router services. The CVSS 3.1 score of 9.1 reflects critical severity, with an attack vector over the network, low attack complexity, requiring privileges (authenticated access), no user interaction, and scope change indicating impact beyond the initially vulnerable component. No public exploits are known yet, but the risk is high due to the critical nature and ease of exploitation once authenticated. The vulnerability underscores the risks of insufficient input validation and access control in embedded device management interfaces, common in IoT and networking hardware. Organizations relying on this router firmware version should prioritize patching or mitigating access to the management interface to prevent exploitation.

For European organizations, this vulnerability poses a significant risk to network infrastructure security. Compromise of the Wavlink AC3000 routers could lead to unauthorized access to internal networks, interception or manipulation of sensitive data, and disruption of network-attached storage services. This can affect business continuity, data confidentiality, and integrity, especially in sectors relying on these devices for critical operations such as SMEs, educational institutions, and small data centers. Given the router’s role in managing NAS configurations, attackers could alter storage settings, potentially leading to data loss or ransomware deployment. The requirement for authentication reduces the risk from remote unauthenticated attackers but does not eliminate it, as credential theft or weak authentication mechanisms could facilitate exploitation. The critical CVSS score reflects the potential for widespread impact if exploited in environments where these devices are deployed without adequate security controls.

1. Immediate mitigation involves restricting access to the router’s management interface to trusted networks and users only, using network segmentation and firewall rules. 2. Enforce strong authentication mechanisms, including complex passwords and, if supported, multi-factor authentication to reduce the risk of credential compromise. 3. Monitor network traffic for unusual HTTP POST requests targeting nas.cgi or FTP configuration endpoints to detect potential exploitation attempts. 4. Disable or limit NAS and FTP services on the router if not required, reducing the attack surface. 5. Regularly audit and update router firmware; although no patch links are currently available, monitor Wavlink advisories for updates addressing this vulnerability. 6. Implement network intrusion detection/prevention systems (IDS/IPS) with signatures tuned to detect exploitation attempts of this vulnerability. 7. Educate administrators on the risks of configuration injection vulnerabilities and the importance of securing device management interfaces. 8. Consider replacing affected devices with models from vendors with stronger security track records if timely patches are not forthcoming.