CVE-2024-51252 identifies a command injection vulnerability in the Draytek Vigor3900 router firmware version 1.5.1.3. The vulnerability resides in the mainfunction.cgi script, specifically within the restore function, which improperly sanitizes user input. This allows an authenticated attacker with low privileges to inject arbitrary commands that the system executes with elevated privileges. The vulnerability is classified under CWE-78 (Improper Neutralization of Special Elements used in an OS Command), indicating that the input validation is insufficient to prevent command injection attacks. The CVSS v3.1 base score is 8.0, reflecting high severity due to the attack vector being adjacent network (AV:A), low attack complexity (AC:L), requiring privileges (PR:L), no user interaction (UI:N), and impacting confidentiality, integrity, and availability (C:H/I:H/A:H). Although no public exploits have been reported, the nature of the vulnerability suggests that exploitation could lead to full system compromise, enabling attackers to manipulate device configurations, intercept or redirect traffic, or disrupt network operations. The lack of available patches at the time of disclosure increases the urgency for defensive measures. This vulnerability affects network infrastructure devices critical for enterprise and service provider environments, making it a significant risk for organizations relying on Draytek Vigor3900 routers.

Successful exploitation of CVE-2024-51252 can have severe consequences for organizations worldwide. Attackers can gain arbitrary command execution on the affected router, potentially leading to full device compromise. This undermines the confidentiality of network traffic, as attackers may intercept or redirect data. Integrity is compromised as attackers can alter device configurations or firmware, enabling persistent backdoors or malicious routing changes. Availability is at risk since attackers can disrupt network services by disabling or misconfiguring the device. Given that routers like the Draytek Vigor3900 often serve as critical network gateways, exploitation can cascade into broader network disruptions, affecting business continuity and security posture. The requirement for low privileges and no user interaction lowers the barrier for attackers, increasing the likelihood of targeted attacks or automated exploitation once public exploits emerge. Organizations in sectors with high reliance on secure and stable network infrastructure, such as finance, government, healthcare, and telecommunications, face heightened risks.

1. Immediate mitigation should focus on restricting access to the router's management interfaces, especially the mainfunction.cgi endpoint, by limiting access to trusted IP addresses and using VPNs or secure management networks. 2. Employ network segmentation to isolate critical network infrastructure devices from general user networks and the internet. 3. Monitor network traffic and device logs for unusual activity indicative of command injection attempts or unauthorized configuration changes. 4. Disable or restrict the restore function in mainfunction.cgi if possible until a patch is available. 5. Engage with Draytek support or vendor channels to obtain firmware updates or patches addressing this vulnerability as soon as they are released. 6. Implement intrusion detection/prevention systems (IDS/IPS) with signatures or heuristics capable of detecting command injection patterns targeting Draytek devices. 7. Conduct regular security audits and vulnerability assessments on network infrastructure to identify and remediate similar issues proactively. 8. Educate network administrators on the risks of command injection vulnerabilities and best practices for secure device management.