CVE-2024-51254 is a command injection vulnerability identified in the DrayTek Vigor3900 router firmware version 1.5.1.3. The vulnerability resides in the mainfunction.cgi web interface, specifically within the sign_cacertificate function, which improperly sanitizes user input. This flaw allows remote attackers to inject malicious commands without authentication, leading to arbitrary command execution on the underlying operating system. The vulnerability is classified under CWE-77 (Improper Neutralization of Special Elements used in a Command), indicating that the input is not correctly validated before being passed to system commands. The CVSS v3.1 base score of 8.8 reflects the high impact on confidentiality, integrity, and availability, with an attack vector over the network, low attack complexity, no privileges required, and no user interaction needed. Exploiting this vulnerability could allow attackers to gain full control over the router, manipulate network traffic, deploy malware, or disrupt network services. Although no public exploits have been reported yet, the severity and ease of exploitation make this a critical threat to affected organizations. The lack of available patches increases the urgency for interim mitigations and monitoring.

The impact of CVE-2024-51254 is significant for organizations relying on DrayTek Vigor3900 routers as a critical network infrastructure component. Successful exploitation can lead to complete compromise of the device, allowing attackers to intercept, modify, or block network traffic, potentially leading to data breaches, espionage, or denial of service. The integrity of network communications can be undermined, and attackers might use the compromised router as a foothold for further attacks within the internal network. This can affect confidentiality by exposing sensitive data, integrity by altering configurations or data flows, and availability by causing network outages. Given the router’s role in enterprise and ISP environments, the disruption could have cascading effects on business operations and service delivery. The absence of authentication and user interaction requirements lowers the barrier for attackers, increasing the likelihood of exploitation if the device is exposed to untrusted networks.

To mitigate CVE-2024-51254, organizations should immediately restrict access to the DrayTek Vigor3900 management interfaces, especially the web interface hosting mainfunction.cgi, by limiting it to trusted internal networks or VPNs. Implement network segmentation to isolate critical infrastructure and reduce exposure. Employ strict firewall rules to block unauthorized inbound traffic targeting the router’s management ports. Monitor network traffic and device logs for unusual activity, particularly requests to mainfunction.cgi or attempts to invoke sign_cacertificate. Disable or restrict unused services and interfaces on the router to minimize attack surface. Until an official patch is released, consider deploying web application firewalls (WAFs) or intrusion prevention systems (IPS) with custom rules to detect and block command injection patterns targeting this vulnerability. Regularly check for firmware updates from DrayTek and apply patches promptly once available. Additionally, maintain an incident response plan to quickly address any signs of compromise.