CVE-2026-1623 identifies a command injection vulnerability in the Totolink A7000R router firmware version 4.1cu.4154. The vulnerability resides in the setUpgradeFW function of the /cgi-bin/cstecgi.cgi endpoint, where the FileName parameter is improperly sanitized, allowing attackers to inject and execute arbitrary system commands. This flaw can be exploited remotely without requiring authentication or user interaction, making it accessible to any attacker with network access to the device. The vulnerability impacts the confidentiality, integrity, and availability of the router by potentially granting full control over the device, enabling attackers to manipulate network traffic, deploy malware, or disrupt services. Although no active exploitation has been reported, the availability of a public exploit increases the likelihood of future attacks. The CVSS 4.0 vector indicates low complexity and no privileges required, but limited scope and impact to the device itself, resulting in a medium severity rating of 5.3. The lack of a vendor patch at the time of reporting necessitates immediate defensive measures to reduce exposure. This vulnerability is particularly concerning for environments where the Totolink A7000R is deployed in critical network roles or where remote management is enabled. Organizations should monitor for suspicious activity targeting the /cgi-bin/cstecgi.cgi endpoint and restrict access to management interfaces.

For European organizations, exploitation of this vulnerability could lead to unauthorized remote control of affected routers, compromising network security and potentially enabling lateral movement within corporate networks. Confidential data passing through the router could be intercepted or altered, and attackers could disrupt network availability by modifying device configurations or launching denial-of-service attacks. The impact is heightened in sectors relying on stable and secure network infrastructure, such as finance, healthcare, and government. Additionally, compromised routers could serve as footholds for broader cyberattacks or be incorporated into botnets for large-scale attacks. The medium severity rating reflects a significant risk that, if unaddressed, could lead to operational disruptions and data breaches. European organizations using Totolink A7000R devices should be aware of these risks and act promptly to mitigate them.

1. Immediately restrict network access to the router’s management interfaces, especially from untrusted networks, by implementing firewall rules or network segmentation. 2. Disable remote management features if not strictly necessary to reduce the attack surface. 3. Monitor network traffic and device logs for unusual activity targeting the /cgi-bin/cstecgi.cgi endpoint or unexpected command execution patterns. 4. Apply firmware updates from Totolink as soon as they become available to patch the vulnerability. 5. If a patch is not yet available, consider replacing affected devices with alternative models that do not have this vulnerability. 6. Employ intrusion detection/prevention systems (IDS/IPS) to detect exploitation attempts based on known indicators or exploit signatures. 7. Educate IT staff about this vulnerability and ensure incident response plans include steps for handling potential router compromises. 8. Conduct regular security audits of network devices to identify and remediate similar vulnerabilities proactively.