CVE-2020-10825 is a critical security vulnerability identified in certain Draytek router devices, specifically the Vigor3900, Vigor2960, and Vigor300B models running firmware versions prior to 1.5.1. The vulnerability is a stack-based buffer overflow occurring in the /cgi-bin/activate.cgi endpoint during the base64 decoding process of the 'ticket' parameter. This flaw allows a remote attacker to send a specially crafted HTTP request that triggers the overflow, enabling arbitrary code execution on the affected device without requiring any authentication or user interaction. The vulnerability is classified under CWE-787 (Out-of-bounds Write), which typically leads to memory corruption and potential control over the execution flow. With a CVSS v3.1 score of 9.8, this vulnerability is rated as critical due to its high impact on confidentiality, integrity, and availability, combined with its ease of exploitation over the network. Exploitation could allow attackers to fully compromise the affected routers, leading to unauthorized access, interception or manipulation of network traffic, and potential pivoting into internal networks. Although no known exploits have been reported in the wild as of the published date, the severity and nature of the vulnerability make it a significant threat to organizations using these devices.

For European organizations, the impact of CVE-2020-10825 could be severe. Draytek routers are commonly deployed in small to medium enterprises and branch offices for secure internet connectivity and VPN services. Successful exploitation could lead to complete compromise of the router, allowing attackers to intercept sensitive communications, inject malicious traffic, disrupt network availability, or establish persistent footholds within corporate networks. This is particularly concerning for organizations handling sensitive personal data under GDPR, as unauthorized access or data leakage could result in regulatory penalties and reputational damage. Additionally, compromised routers could be leveraged as launch points for broader attacks against critical infrastructure or supply chains within Europe. The lack of authentication and user interaction requirements increases the risk of automated exploitation attempts, potentially affecting a wide range of organizations across sectors such as finance, healthcare, manufacturing, and government.

To mitigate this vulnerability, European organizations should prioritize the following actions: 1) Immediately identify and inventory all Draytek Vigor3900, Vigor2960, and Vigor300B devices in their environment. 2) Upgrade the firmware on these devices to version 1.5.1 or later, where the vulnerability has been addressed. If an upgrade is not immediately possible, consider temporarily disabling remote access to the /cgi-bin/activate.cgi endpoint or restricting access to trusted IP addresses only. 3) Implement network segmentation to isolate critical assets from potentially vulnerable routers. 4) Monitor network traffic for unusual HTTP requests targeting the activate.cgi endpoint or signs of exploitation attempts. 5) Employ intrusion detection/prevention systems (IDS/IPS) with updated signatures to detect attempts to exploit this vulnerability. 6) Regularly review and update router configurations to follow security best practices, including disabling unnecessary services and enforcing strong administrative credentials. 7) Engage with Draytek support or authorized vendors for guidance and support in patch management and incident response related to this vulnerability.