CVE-2024-39785 is a critical command injection vulnerability identified in the Wavlink AC3000 router firmware version M33A8.V5030.210505. The flaw exists in the nas.cgi add_dir() functionality, specifically in the handling of the adddir_name POST parameter. This parameter is improperly sanitized, allowing special characters or command sequences to be injected and executed by the underlying system shell. An attacker with valid authentication credentials can craft a malicious HTTP POST request to the nas.cgi endpoint, exploiting this injection to execute arbitrary system commands with the privileges of the web server process, which typically runs with elevated rights on the device. The vulnerability is classified under CWE-74 (Improper Neutralization of Special Elements in Output Used by a Downstream Component), indicating that the input is not properly sanitized before being passed to a downstream command interpreter. The CVSS 3.1 base score of 9.1 reflects the vulnerability’s critical nature, with network attack vector, low attack complexity, required privileges (authenticated), no user interaction, and scope change. The impact includes full compromise of confidentiality, integrity, and availability of the affected device, enabling attackers to manipulate device configurations, intercept or redirect traffic, or use the device as a pivot point for further network attacks. Although no known exploits have been reported in the wild yet, the vulnerability’s characteristics make it a high-risk target for attackers once exploit code becomes available. The lack of an official patch at the time of publication necessitates immediate mitigation efforts to reduce exposure.

For European organizations, exploitation of CVE-2024-39785 could lead to complete compromise of affected Wavlink AC3000 routers, which are often deployed in small to medium enterprise and home office environments. Attackers gaining control over these devices can intercept sensitive communications, disrupt network availability, or use the compromised routers as footholds for lateral movement into corporate networks. This is particularly concerning for sectors relying on secure and reliable network infrastructure, such as finance, healthcare, and critical infrastructure. The vulnerability’s ability to impact confidentiality, integrity, and availability simultaneously means that data breaches, service outages, and unauthorized access to internal systems are realistic outcomes. Given the router’s role as a network gateway, the threat extends beyond the device itself to the entire connected network segment. The requirement for authentication limits exposure to some extent but does not eliminate risk, especially if default or weak credentials are used. The absence of known exploits currently provides a small window for proactive defense, but the critical severity score demands urgent attention.

1. Immediately audit all Wavlink AC3000 devices in your environment to identify affected firmware versions (M33A8.V5030.210505). 2. Enforce strong, unique administrative passwords to prevent unauthorized authentication. 3. Restrict management interface access to trusted IP addresses or via VPN to reduce exposure to authenticated attackers. 4. Implement network segmentation to isolate vulnerable devices from critical network segments. 5. Monitor network traffic and device logs for unusual HTTP POST requests to nas.cgi or other suspicious activity indicative of exploitation attempts. 6. Disable remote management interfaces if not strictly necessary. 7. Engage with Wavlink or authorized vendors to obtain and apply firmware updates or patches as soon as they become available. 8. Consider deploying intrusion detection/prevention systems (IDS/IPS) with signatures targeting command injection attempts on nas.cgi endpoints. 9. Educate network administrators about the risks of command injection vulnerabilities and the importance of timely patching and access control. 10. Maintain an inventory of all network devices and their firmware versions to facilitate rapid response to emerging threats.