CVE-2020-10824 is a critical security vulnerability identified as a stack-based buffer overflow in the /cgi-bin/activate.cgi endpoint of Draytek Vigor series routers, specifically the Vigor3900, Vigor2960, and Vigor300B models running firmware versions prior to 1.5.1. The vulnerability arises from improper handling of the 'ticket' parameter in HTTP requests, allowing a remote attacker to send a specially crafted HTTP request that overflows the stack buffer. This overflow can lead to arbitrary code execution on the affected device without requiring authentication or user interaction. The vulnerability is classified under CWE-787 (Out-of-bounds Write), indicating that the flaw involves writing data outside the intended buffer boundaries, which can corrupt memory and enable control over the execution flow. The CVSS v3.1 base score of 9.8 reflects its critical severity, with attack vector being network-based (AV:N), no privileges required (PR:N), no user interaction (UI:N), and full impact on confidentiality, integrity, and availability (C:H/I:H/A:H). Although no known exploits have been reported in the wild, the ease of exploitation and the critical impact make this vulnerability a significant threat to organizations using these Draytek devices. The absence of patch links suggests that users must verify firmware updates directly from the vendor to remediate this issue.

For European organizations, this vulnerability poses a severe risk, especially for those relying on Draytek Vigor3900, Vigor2960, or Vigor300B routers for network perimeter security, VPN connectivity, or internal segmentation. Successful exploitation can lead to complete compromise of the affected device, allowing attackers to execute arbitrary code, potentially gaining persistent access to the network, intercepting or manipulating sensitive data, disrupting network availability, or using the device as a pivot point for further attacks. Given the critical nature of the flaw and the lack of required authentication, attackers can remotely exploit vulnerable devices over the internet, increasing the attack surface. This is particularly concerning for organizations in sectors with stringent data protection requirements such as finance, healthcare, and critical infrastructure within Europe. The compromise of these routers could lead to violations of GDPR due to unauthorized data access or service disruptions. Additionally, the disruption of network services could impact business continuity and operational resilience.

European organizations should immediately verify if they are using any of the affected Draytek Vigor models and check the firmware version. They must upgrade to firmware version 1.5.1 or later, where the vulnerability has been addressed. If immediate patching is not possible, organizations should restrict access to the router's management interfaces by implementing network segmentation and firewall rules to limit exposure of the /cgi-bin/activate.cgi endpoint to trusted internal networks only. Employing intrusion detection/prevention systems (IDS/IPS) with signatures targeting exploit attempts against this vulnerability can help detect and block malicious traffic. Regularly monitoring router logs for unusual activity related to HTTP requests on the activate.cgi endpoint is recommended. Additionally, organizations should consider disabling remote management features if not required and enforce strong network perimeter defenses. Vendor communication channels should be monitored for any released patches or advisories. Finally, conducting a comprehensive network audit to identify and remediate any unauthorized access or compromise resulting from this vulnerability is critical.