CVE-2026-1689: Tenda HG10 Command Injection Vulnerability

CVE-2026-1689 Overview

A command injection vulnerability has been identified in the Tenda HG10 router running firmware version US_HG7_HG9_HG10re_300001138_en_xpon. The vulnerability exists in the checkUserFromLanOrWan function within the /boaform/admin/formLogin endpoint of the Login Interface component. By manipulating the Host argument, an attacker can inject arbitrary operating system commands that are executed by the device. This vulnerability can be exploited remotely without authentication, making it a significant risk for organizations using affected Tenda networking equipment.

Critical Impact

Remote command injection in the login interface allows unauthenticated attackers to execute arbitrary system commands on vulnerable Tenda HG10 routers, potentially leading to full device compromise, network pivoting, and persistent backdoor installation.

Affected Products

• Tenda HG10 (Firmware: US_HG7_HG9_HG10re_300001138_en_xpon)
• Tenda HG7 series (potentially affected)
• Tenda HG9 series (potentially affected)

Discovery Timeline

• 2026-01-30 - CVE CVE-2026-1689 published to NVD
• 2026-02-04 - Last updated in NVD database

Technical Details for CVE-2026-1689

Vulnerability Analysis

This command injection vulnerability (CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component) stems from inadequate input validation in the Tenda HG10 router's web administration interface. The checkUserFromLanOrWan function processes the Host parameter without proper sanitization, allowing attackers to inject shell metacharacters and arbitrary commands that are subsequently executed by the underlying operating system.

The vulnerability is accessible via the network without requiring authentication, which significantly increases its exploitability. The public availability of exploit code further elevates the risk, as threat actors can readily weaponize this vulnerability against exposed devices. Successful exploitation grants attackers the ability to execute commands with the privileges of the web server process, typically root on embedded devices like routers.

Root Cause

The root cause of this vulnerability is improper input validation in the checkUserFromLanOrWan function. The function fails to sanitize or validate the Host argument before incorporating it into system command execution. This allows special characters and shell metacharacters (such as ;, |, &&, or backticks) to be interpreted as command delimiters, enabling arbitrary command injection. The affected code path exists in the /boaform/admin/formLogin endpoint, which is part of the device's administrative login interface and should never trust user-controlled input.

Attack Vector

The attack vector is network-based, targeting the web administration interface of vulnerable Tenda HG10 devices. An attacker can craft a malicious HTTP request to the /boaform/admin/formLogin endpoint with a specially crafted Host parameter containing injected commands. Since no authentication is required to reach this vulnerable code path, any attacker with network access to the device can exploit this flaw.

The exploitation technique involves injecting shell commands into the Host parameter using command chaining operators or shell metacharacters. When the vulnerable function processes this input, the injected commands are executed on the device. Attackers could leverage this to download and execute malware, establish reverse shells, modify device configurations, or use the compromised router as a pivot point for lateral movement within the network.

For detailed technical information and proof-of-concept examples, refer to the GitHub PoC Documentation.

Detection Methods for CVE-2026-1689

Indicators of Compromise

• Unusual outbound connections from router devices to unknown external IP addresses
• HTTP POST requests to /boaform/admin/formLogin containing shell metacharacters (;, |, &&, backticks) in the Host parameter
• Unexpected processes or network connections originating from the router
• Modified router configurations or newly created user accounts

Detection Strategies

• Deploy network intrusion detection rules to identify HTTP requests with command injection patterns targeting /boaform/admin/formLogin
• Monitor web server logs on network appliances for requests containing shell metacharacters in HTTP parameters
• Implement network segmentation to limit exposure of router administration interfaces and alert on unauthorized access attempts
• Use SentinelOne Singularity for network visibility to detect anomalous traffic patterns from IoT and network devices

Monitoring Recommendations

• Establish baseline network behavior for Tenda routers and alert on deviations such as new outbound connections or unusual traffic volumes
• Configure SIEM rules to correlate access attempts to router administration interfaces with subsequent suspicious network activity
• Regularly audit router configurations and compare against known-good baselines to detect unauthorized changes

How to Mitigate CVE-2026-1689

Immediate Actions Required

• Restrict network access to the router's web administration interface by implementing firewall rules or access control lists
• Disable remote administration if not required for business operations
• Isolate affected Tenda HG10 devices on a separate network segment with strict egress filtering
• Monitor for indicators of compromise on potentially exposed devices

Patch Information

At the time of publication, no official patch has been released by Tenda. Organizations should monitor the Tenda Official Website for firmware updates addressing this vulnerability. Given the public availability of exploit details, applying patches immediately upon release is strongly recommended. Additional vulnerability details can be found at VulDB #343483.

Workarounds

• Implement network-level access controls to restrict access to the /boaform/admin/formLogin endpoint to trusted IP addresses only
• Deploy a web application firewall (WAF) or reverse proxy with rules to filter requests containing command injection patterns
• Consider replacing vulnerable devices with alternative networking equipment if patches are not available in a timely manner
• Use VPN or other secure remote access methods instead of exposing the router's web interface directly

# Example iptables rule to restrict access to router admin interface
# Replace 192.168.1.0/24 with your trusted management network
iptables -A INPUT -p tcp --dport 80 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP