CVE-2024-39765 is a critical OS command injection vulnerability identified in the Wavlink AC3000 router firmware version M33A8.V5030.210505. The flaw resides in the internet.cgi script’s set_add_routing() function, where improper neutralization of special elements in the custom_interface POST parameter allows an authenticated attacker to inject arbitrary OS commands. This vulnerability is classified under CWE-77, indicating improper sanitization of input leading to command injection. Exploitation requires the attacker to be authenticated to the device’s web management interface but does not require user interaction beyond that. The vulnerability enables execution of arbitrary commands with the privileges of the web server process, potentially leading to full device compromise, including control over routing, interception or modification of network traffic, and denial of service. The CVSS v3.1 score of 9.1 (AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H) reflects a network attack vector with low complexity, requiring high privileges (authenticated access), no user interaction, and complete impact on confidentiality, integrity, and availability with scope change. No patches or public exploits are currently available, but the critical nature of this vulnerability necessitates urgent mitigation. The vulnerability’s presence in a widely deployed router model used in enterprise and consumer environments raises concerns about potential lateral movement and persistent footholds within affected networks.

For European organizations, exploitation of CVE-2024-39765 could lead to severe consequences including unauthorized control over network routing, interception of sensitive communications, and disruption of internet connectivity. Compromise of the Wavlink AC3000 routers could allow attackers to pivot into internal networks, exfiltrate confidential data, or launch further attacks against critical infrastructure. The vulnerability’s ability to affect confidentiality, integrity, and availability simultaneously makes it particularly dangerous for sectors such as finance, healthcare, government, and telecommunications. Given the router’s role as a network gateway, successful exploitation could undermine trust in network security and cause operational downtime. Additionally, the lack of public exploits currently means organizations may be caught unprepared if threat actors develop weaponized payloads. The requirement for authenticated access somewhat limits remote exploitation but does not eliminate risk, especially in environments with weak or default credentials or exposed management interfaces.

Immediate mitigation steps include restricting access to the router’s web management interface to trusted internal networks and enforcing strong authentication policies to prevent unauthorized access. Network segmentation should be implemented to isolate management interfaces from general user traffic. Organizations should monitor network traffic for unusual HTTP requests targeting the internet.cgi endpoint and the set_add_routing() function. Since no official patches are currently available, consider replacing affected devices with updated models or alternative vendors that have addressed this vulnerability. Employing Web Application Firewalls (WAFs) or Intrusion Prevention Systems (IPS) with custom rules to detect and block command injection patterns in HTTP POST requests can provide additional protection. Regularly audit router configurations and credentials to ensure no default or weak passwords are in use. Finally, maintain vigilance for vendor updates or security advisories that provide patches or further guidance.