CVE-2024-39784 is a critical command injection vulnerability identified in the Wavlink AC3000 router firmware version M33A8.V5030.210505. The flaw resides in the nas.cgi add_dir() functionality, specifically within the disk_part POST parameter, which fails to properly neutralize special elements before passing input to downstream components. This improper input sanitization (CWE-74) allows an authenticated attacker to craft HTTP POST requests that inject arbitrary commands executed by the underlying operating system. The vulnerability requires the attacker to have valid authentication credentials to the device's web interface but does not require any additional user interaction. Successful exploitation can lead to complete device compromise, enabling attackers to execute arbitrary code, manipulate device configurations, intercept or redirect network traffic, or launch further attacks within the network. The vulnerability has a CVSS v3.1 base score of 9.1, reflecting its critical severity with network attack vector, low attack complexity, high privileges required, no user interaction, and impacts to confidentiality, integrity, and availability with scope change. Although no exploits are currently known in the wild, the critical nature and ease of exploitation post-authentication make this a significant threat. The lack of an available patch at the time of publication increases the urgency for organizations to implement interim mitigations.

For European organizations, the impact of CVE-2024-39784 can be severe. Wavlink AC3000 routers are often deployed in small to medium business and home office environments, but may also be present in branch offices of larger enterprises. Exploitation can lead to full device compromise, allowing attackers to intercept sensitive communications, disrupt network availability, or pivot into internal networks to escalate attacks. This can result in data breaches, operational downtime, and potential regulatory non-compliance under GDPR due to unauthorized access to personal data. Critical sectors such as finance, healthcare, and government agencies using these devices are particularly at risk. The requirement for authentication limits exposure to some extent, but stolen or weak credentials can be leveraged by attackers. The absence of known exploits in the wild currently reduces immediate risk, but the critical severity and potential for rapid weaponization necessitate proactive defense. Additionally, compromised routers can be used as footholds for broader cyber espionage or ransomware campaigns targeting European entities.

1. Immediately restrict administrative access to the Wavlink AC3000 web interface by limiting it to trusted IP addresses or internal networks only. 2. Enforce strong, unique passwords and implement multi-factor authentication if supported to reduce the risk of credential compromise. 3. Monitor network traffic for unusual HTTP POST requests targeting nas.cgi endpoints, particularly those with suspicious disk_part parameters. 4. Disable remote management features if not required to minimize exposure. 5. Regularly audit router firmware versions and configurations to identify affected devices. 6. Engage with Wavlink support or vendor channels to obtain and apply firmware updates or patches as soon as they become available. 7. Consider network segmentation to isolate vulnerable devices from critical infrastructure. 8. Employ intrusion detection systems (IDS) or endpoint detection and response (EDR) solutions capable of detecting anomalous command injection attempts. 9. Educate network administrators on this vulnerability and the importance of credential security. 10. Prepare incident response plans to quickly remediate any detected exploitation attempts.