CVE-2024-39770 is a critical security vulnerability classified under CWE-120 (Classic Buffer Overflow) affecting the Wavlink AC3000 router firmware version M33A8.V5030.210505. The flaw resides in the internet.cgi set_qos() function, specifically in the processing of the en_enable POST parameter. This parameter is vulnerable to a stack-based buffer overflow when a specially crafted HTTP request is sent by an attacker who has authenticated access to the device’s web interface. The overflow can overwrite the stack, potentially allowing arbitrary code execution, privilege escalation, or denial of service. The vulnerability’s CVSS 3.1 base score is 9.1, reflecting its critical impact on confidentiality, integrity, and availability, with network attack vector, low attack complexity, and high privileges required but no user interaction needed. Although no known exploits are publicly reported, the vulnerability’s nature and criticality make it a high-risk target for attackers aiming to compromise network infrastructure. The lack of available patches at the time of publication increases the urgency for mitigations. This vulnerability could be exploited remotely by authenticated users, such as internal attackers or compromised credentials, to gain control over the router, potentially pivoting into internal networks or disrupting network services.

For European organizations, exploitation of CVE-2024-39770 could lead to severe consequences including unauthorized access to internal networks, interception or manipulation of network traffic, and disruption of critical services. Given the router’s role as a network gateway, a successful attack could compromise the confidentiality of sensitive data, integrity of communications, and availability of network resources. This is particularly impactful for sectors such as finance, healthcare, government, and critical infrastructure where network reliability and security are paramount. The requirement for authentication limits exposure to external unauthenticated attackers but does not eliminate risk, as credential compromise or insider threats could enable exploitation. The vulnerability could also facilitate lateral movement within corporate networks, increasing the potential damage. The absence of known exploits currently provides a window for proactive defense, but the critical severity score indicates that exploitation could have widespread and damaging effects.

1. Immediately restrict access to the router’s web management interface to trusted internal networks and trusted administrators only, using network segmentation and firewall rules. 2. Enforce strong authentication mechanisms and regularly rotate credentials to reduce the risk of credential compromise. 3. Monitor web server logs and network traffic for anomalous or suspicious HTTP POST requests targeting the internet.cgi set_qos() endpoint, especially those containing unusual en_enable parameter values. 4. Disable or limit QoS configuration access via the web interface if not required operationally. 5. Engage with Wavlink support or vendor channels to obtain and apply firmware updates or patches as soon as they become available. 6. Implement network intrusion detection/prevention systems (IDS/IPS) with signatures or heuristics to detect exploitation attempts targeting this vulnerability. 7. Conduct internal security awareness and training to prevent insider threats and credential misuse. 8. Consider temporary compensating controls such as VPN access restrictions or multi-factor authentication for router management interfaces.