CVE-2024-39786 is a critical security vulnerability classified as CWE-22 (Improper Limitation of a Pathname to a Restricted Directory), affecting the Wavlink AC3000 router firmware version M33A8.V5030.210505. The vulnerability resides in the nas.cgi add_dir() functionality, where the adddir_name POST parameter is improperly sanitized, allowing directory traversal attacks. An authenticated attacker can craft a specially formed HTTP POST request to manipulate the adddir_name parameter, enabling them to traverse directories outside the intended restricted path. This results in permission bypass, potentially allowing unauthorized access to sensitive files, modification or deletion of critical system files, and disruption of device operations. The vulnerability is remotely exploitable over the network without requiring user interaction, but it does require attacker authentication, which may limit exposure to some extent. The CVSS v3.1 score of 9.1 reflects the vulnerability's critical nature, with high impact on confidentiality, integrity, and availability, and low attack complexity. No patches are currently linked, and no known exploits have been reported in the wild, but the risk remains significant due to the severity and potential for exploitation. The vulnerability affects a specific firmware version, so organizations using this exact version are at risk. The nas.cgi interface is typically used for managing network-attached storage functions, meaning exploitation could compromise stored data and device stability.

For European organizations, exploitation of CVE-2024-39786 could lead to severe consequences including unauthorized access to sensitive data stored on network-attached storage managed by the Wavlink AC3000 device, modification or deletion of critical files, and potential full device compromise. This could disrupt business operations, lead to data breaches involving personal or corporate information, and impact availability of network services. Organizations in sectors such as telecommunications, finance, healthcare, and critical infrastructure that rely on Wavlink AC3000 routers for network management or storage are particularly vulnerable. The requirement for authentication reduces the risk from external unauthenticated attackers but insider threats or compromised credentials could be leveraged to exploit this vulnerability. The critical severity and scope of impact necessitate urgent attention to prevent lateral movement or escalation of privileges within networks. Additionally, disruption of network services could affect compliance with European data protection regulations such as GDPR if personal data is exposed or lost.

1. Monitor Wavlink’s official channels for firmware updates addressing CVE-2024-39786 and apply patches immediately upon release. 2. Until patches are available, restrict administrative access to the Wavlink AC3000 device to trusted networks and users only, employing network segmentation and VPNs where possible. 3. Enforce strong authentication mechanisms and regularly audit credentials to prevent unauthorized access. 4. Implement web application firewall (WAF) rules to detect and block suspicious HTTP POST requests targeting nas.cgi, especially those containing directory traversal patterns in the adddir_name parameter. 5. Conduct regular security assessments and penetration tests focusing on network-attached storage and router interfaces to detect similar vulnerabilities. 6. Maintain comprehensive logging and monitoring of device access and configuration changes to quickly identify exploitation attempts. 7. Educate IT staff about the risks of directory traversal vulnerabilities and the importance of timely patching and access controls. 8. Consider isolating or replacing vulnerable devices in critical environments if immediate patching is not feasible.