CVE-2026-1689 is a command injection vulnerability identified in the Tenda HG10 router firmware version US_HG7_HG9_HG10re_300001138_en_xpon. The vulnerability resides in the checkUserFromLanOrWan function of the /boaform/admin/formLogin component, which handles login requests. Specifically, the Host argument passed to this function is not properly sanitized, allowing an attacker to inject arbitrary shell commands. This flaw can be exploited remotely without requiring authentication or user interaction, making it highly accessible to attackers. The vulnerability enables an attacker to execute arbitrary commands on the device with the privileges of the web server process, potentially leading to full device compromise, unauthorized network access, or pivoting to internal networks. The CVSS 4.0 vector indicates network attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:N), no user interaction (UI:N), and partial impacts on confidentiality, integrity, and availability (VC:L, VI:L, VA:L). Although no patches or official fixes have been published yet, a public exploit is available, increasing the risk of exploitation. The affected product is primarily deployed as a home or small office gateway device, often providing internet access and routing capabilities. The vulnerability's exploitation could allow attackers to manipulate network traffic, intercept sensitive data, or disrupt network availability.

For European organizations, especially small businesses and residential users relying on Tenda HG10 routers, this vulnerability poses a significant risk. Successful exploitation could lead to unauthorized control over the router, enabling attackers to intercept or manipulate network traffic, deploy malware, or use the compromised device as a foothold for further attacks within the internal network. This could result in data breaches, loss of confidentiality, and potential disruption of internet connectivity. Given the router's role as a network gateway, the impact extends beyond the device itself to the broader network environment. The lack of authentication and user interaction requirements lowers the barrier for attackers, increasing the likelihood of exploitation. Organizations with remote management enabled or exposed router interfaces are particularly vulnerable. The medium CVSS score reflects the balance between the ease of exploitation and the partial impact on system security, but the presence of a public exploit elevates the urgency for mitigation.

1. Immediately disable remote management interfaces on affected Tenda HG10 devices to reduce exposure to external attackers. 2. Restrict access to the router's administrative interface to trusted internal networks only, using firewall rules or access control lists. 3. Implement network segmentation to isolate IoT and router devices from critical business systems, limiting lateral movement if compromised. 4. Monitor network traffic for unusual patterns or command injection attempts targeting the login interface. 5. Regularly audit router firmware versions and configurations to identify and replace vulnerable devices. 6. Until an official patch is released, consider replacing affected devices with models from vendors with timely security updates. 7. Educate users on the risks of exposing router management interfaces and encourage strong, unique administrative passwords. 8. Employ intrusion detection/prevention systems capable of detecting command injection attempts on network devices. 9. Follow vendor communications closely for patch releases and apply updates promptly once available.