CVE-2025-28017 is a command injection vulnerability identified in the TOTOLINK A800R router firmware version 4.1.2cu.5032_B20200408. The vulnerability exists in the handling of the downloadFile.cgi endpoint, specifically via the QUERY_STRING parameter. Command injection (CWE-77) vulnerabilities allow an attacker to inject and execute arbitrary commands on the underlying operating system. In this case, the vulnerability is remotely exploitable over the network (AV:N), requires no privileges (PR:N), and no user interaction (UI:N), making it accessible to unauthenticated attackers. The CVSS 3.1 base score is 6.5, indicating a medium severity level, with impacts primarily on confidentiality and integrity but no direct impact on availability. Exploiting this vulnerability could allow an attacker to execute arbitrary commands on the router, potentially leading to unauthorized access to sensitive information, manipulation of router configurations, or pivoting into internal networks. However, there are no known exploits in the wild at this time, and no official patches have been published. The vulnerability was reserved in March 2025 and publicly disclosed in April 2025. The lack of vendor or product details beyond the TOTOLINK A800R model limits the scope of precise mitigation and impact assessment, but the technical details confirm the critical nature of the command injection vector through the CGI interface, a common attack surface in embedded network devices.

For European organizations, the exploitation of this vulnerability in TOTOLINK A800R routers could compromise network perimeter security. These routers are typically used in small to medium business environments and home offices, which may serve as entry points to corporate networks or sensitive data repositories. Successful exploitation could lead to unauthorized command execution, enabling attackers to intercept or manipulate network traffic, exfiltrate credentials, or establish persistent backdoors. This could undermine confidentiality and integrity of communications and data. Given the router’s role as a network gateway, attackers could also use it to launch further attacks against internal systems. The absence of availability impact reduces the likelihood of direct denial-of-service conditions, but stealthy compromise remains a significant risk. European organizations with remote or distributed workforces relying on such consumer-grade or SMB network equipment are particularly vulnerable. The lack of patches increases exposure, especially if organizations have not implemented compensating controls or network segmentation. Additionally, the vulnerability could be leveraged in targeted attacks against sectors with high-value data or critical infrastructure, increasing the potential for espionage or sabotage.

1. Immediate network-level mitigation: Block external access to the router’s management interfaces, especially the downloadFile.cgi endpoint, using firewall rules or network segmentation to limit exposure. 2. Replace or upgrade: Where possible, upgrade the router firmware to a version that addresses this vulnerability once available. If no patch is provided, consider replacing the device with a more secure alternative. 3. Disable unnecessary services: Disable the CGI interface or remote management features if not required, reducing the attack surface. 4. Monitor network traffic: Implement IDS/IPS rules to detect unusual command injection patterns or suspicious requests targeting downloadFile.cgi or similar endpoints. 5. Conduct internal audits: Identify all TOTOLINK A800R devices within the network and verify their firmware versions and configurations. 6. Harden router configurations: Change default credentials, enforce strong authentication where possible, and restrict management access to trusted IP addresses only. 7. Incident response readiness: Prepare for potential exploitation by establishing logging and alerting mechanisms on network devices and endpoints to detect lateral movement or unusual activity stemming from compromised routers. 8. User awareness: Educate users about the risks of using vulnerable network devices and encourage reporting of unusual network behavior.