CVE-2024-39795 is a critical vulnerability classified under CWE-15 (External Control of System or Configuration Setting) affecting the Wavlink AC3000 router firmware version M33A8.V5030.210505. The flaw resides in the nas.cgi set_nas() function related to the proftpd service, where multiple external configuration control vulnerabilities allow an attacker to inject malicious configuration parameters. Specifically, the ftp_max_sessions POST parameter can be manipulated via a specially crafted HTTP request to bypass permission checks. Although the attacker must be authenticated to the device's HTTP interface, no additional user interaction is required. Exploiting this vulnerability can lead to unauthorized changes in system configuration, resulting in full compromise of confidentiality, integrity, and availability of the device and potentially the network it protects. The vulnerability has a CVSS 3.1 base score of 9.1, reflecting its critical impact and ease of exploitation given low attack complexity and no user interaction. While no exploits are currently known in the wild, the vulnerability poses a significant risk to organizations relying on this router model. The nas.cgi script's improper validation of configuration parameters allows attackers to escalate privileges and manipulate system settings, which could be leveraged to disrupt network services, intercept or alter data, or create persistent backdoors. This vulnerability highlights the risks of insufficient input validation and improper access control in embedded device management interfaces.

For European organizations, the impact of CVE-2024-39795 can be severe. The Wavlink AC3000 router is commonly used in small to medium enterprise and home office environments, which are often less rigorously secured. Exploitation could lead to unauthorized configuration changes, enabling attackers to intercept sensitive communications, disrupt network availability, or pivot deeper into corporate networks. This can result in data breaches, operational downtime, and loss of trust. Critical infrastructure sectors relying on these devices for network connectivity could face service outages or targeted attacks. The requirement for authentication limits exploitation to insiders or attackers who have obtained credentials, but credential theft or reuse is common, increasing risk. The vulnerability’s ability to compromise confidentiality, integrity, and availability simultaneously means that organizations could suffer comprehensive network compromise. Additionally, the lack of current patches or known exploits means organizations must proactively mitigate risk before attackers develop exploits.

European organizations should implement the following specific mitigations: 1) Immediately restrict administrative HTTP access to the Wavlink AC3000 devices by limiting access to trusted IP addresses and enforcing strong authentication mechanisms such as multi-factor authentication. 2) Monitor router logs and network traffic for unusual configuration changes or HTTP POST requests targeting nas.cgi or proftpd-related endpoints. 3) Disable or restrict the proftpd service if not required, reducing the attack surface. 4) Regularly audit and rotate administrative credentials to prevent unauthorized access. 5) Segregate network segments to isolate vulnerable devices from critical infrastructure and sensitive data. 6) Engage with Wavlink for firmware updates or patches addressing this vulnerability and apply them promptly once available. 7) Employ network intrusion detection systems (NIDS) with signatures or heuristics to detect exploitation attempts targeting this vulnerability. 8) Educate IT staff about the risks of configuration injection vulnerabilities and the importance of secure device management. These measures go beyond generic advice by focusing on access control, monitoring, and network segmentation tailored to this specific vulnerability and device context.