CVE-2024-39761 is a critical OS command injection vulnerability identified in the Wavlink AC3000 router firmware version M33A8.V5030.210505. The flaw resides in the login.cgi script’s set_sys_init() function, where the restart_week_value POST parameter is improperly sanitized, allowing an attacker to inject arbitrary OS commands. This vulnerability is exploitable remotely over the network without authentication or user interaction, making it highly dangerous. By sending a specially crafted HTTP request to the vulnerable endpoint, an attacker can execute arbitrary commands with the privileges of the web server process, potentially leading to full device compromise. The vulnerability is classified under CWE-77 (Improper Neutralization of Special Elements used in a Command), indicating a failure to properly sanitize input before passing it to system commands. The CVSS v3.1 score is 10.0, reflecting the highest severity due to network attack vector, no required privileges, no user interaction, and complete impact on confidentiality, integrity, and availability. Although no known exploits are currently reported in the wild, the ease of exploitation and severity make it a critical threat. The affected product, Wavlink AC3000, is a widely used tri-band wireless router, often deployed in small to medium business and home environments. The lack of available patches at the time of disclosure increases the urgency for mitigation. Attackers exploiting this vulnerability could gain persistent control over the device, intercept or manipulate network traffic, or pivot to internal networks.

For European organizations, this vulnerability poses a severe risk to network security and operational continuity. Compromise of Wavlink AC3000 routers could lead to unauthorized access to internal networks, interception of sensitive data, disruption of network services, and potential lateral movement to other critical systems. Small and medium enterprises, as well as home office environments relying on these routers, are particularly vulnerable due to typically weaker perimeter defenses. Critical infrastructure sectors using these devices for network connectivity could face operational disruptions or espionage risks. The unauthenticated nature of the exploit means attackers can target exposed devices directly from the internet, increasing the attack surface. The full compromise potential threatens confidentiality, integrity, and availability of organizational data and services. Additionally, the vulnerability could be leveraged in botnet campaigns or ransomware attacks, amplifying its impact across Europe.

1. Immediately restrict access to the router’s web management interface by implementing network-level controls such as firewall rules or VPN-only access. 2. Disable remote management features if not strictly necessary to reduce exposure. 3. Monitor network traffic for unusual HTTP requests targeting login.cgi or abnormal command execution patterns. 4. Replace or isolate vulnerable Wavlink AC3000 devices until a vendor patch is released. 5. Regularly check Wavlink’s official channels for firmware updates addressing this vulnerability and apply them promptly. 6. Employ network segmentation to limit the impact of potential device compromise. 7. Use intrusion detection/prevention systems (IDS/IPS) with signatures for command injection attempts targeting this router model. 8. Educate IT staff about this vulnerability to ensure rapid response and mitigation. 9. Consider deploying endpoint detection on critical systems to detect lateral movement originating from compromised routers.