CVE-2026-1690: Tenda HG10 Router RCE Vulnerability

CVE-2026-1690 Overview

A command injection vulnerability has been identified in Tenda HG10 routers running firmware version US_HG7_HG9_HG10re_300001138_en_xpon. The flaw exists within the system function of the /boaform/formSysCmd endpoint, where improper handling of the sysCmd argument allows authenticated attackers to inject and execute arbitrary system commands. The attack can be initiated remotely over the network, and proof-of-concept exploit code has been publicly disclosed.

Critical Impact

Authenticated attackers can execute arbitrary commands on affected Tenda HG10 devices, potentially leading to complete device compromise, network pivoting, and persistent access to the target infrastructure.

Affected Products

• Tenda HG10 (firmware version US_HG7_HG9_HG10re_300001138_en_xpon)
• Tenda HG7 (firmware version US_HG7_HG9_HG10re_300001138_en_xpon)
• Tenda HG9 (firmware version US_HG7_HG9_HG10re_300001138_en_xpon)

Discovery Timeline

• 2026-01-30 - CVE-2026-1690 published to NVD
• 2026-02-04 - Last updated in NVD database

Technical Details for CVE-2026-1690

Vulnerability Analysis

This command injection vulnerability (CWE-74) affects the web management interface of Tenda HG10 series routers. The vulnerable endpoint /boaform/formSysCmd implements a diagnostic system command interface that fails to properly sanitize user-supplied input before passing it to the underlying system shell.

When an authenticated user submits a request to this endpoint, the sysCmd parameter value is directly incorporated into a system call without adequate input validation or sanitization. This allows an attacker with valid administrative credentials to append or inject arbitrary shell commands that will be executed with the privileges of the web server process, typically running as root on embedded devices.

The vulnerability requires authenticated access, meaning an attacker must first obtain valid credentials for the device's management interface. However, many Tenda devices ship with default credentials that are frequently left unchanged in production deployments, lowering the practical barrier to exploitation.

Root Cause

The root cause of this vulnerability is improper input validation within the system function handler in /boaform/formSysCmd. The code fails to implement proper sanitization or escaping of shell metacharacters in the sysCmd parameter before passing the input to a system shell execution function. This is a classic command injection pattern where user input is trusted and concatenated directly into command strings.

Attack Vector

The attack is conducted over the network by sending a malicious HTTP request to the /boaform/formSysCmd endpoint. An authenticated attacker can craft a request where the sysCmd parameter contains shell metacharacters (such as ;, |, &&, or backticks) followed by arbitrary commands. When processed by the vulnerable function, these injected commands are executed on the underlying operating system.

The vulnerability mechanism involves crafting HTTP POST requests to the /boaform/formSysCmd endpoint with malicious payloads in the sysCmd parameter. Attackers can leverage shell metacharacters to chain arbitrary commands with the legitimate system diagnostic function. Technical details and proof-of-concept documentation are available in the GitHub PoC Repository.

Detection Methods for CVE-2026-1690

Indicators of Compromise

• Unexpected HTTP POST requests to /boaform/formSysCmd containing shell metacharacters (;, |, &&, `)
• Unusual outbound network connections from the router to unknown external IP addresses
• Presence of unauthorized files or processes on the device indicating backdoor installation
• Anomalous DNS queries or command-and-control communication patterns originating from the device

Detection Strategies

• Implement network intrusion detection rules to monitor for HTTP requests to /boaform/formSysCmd containing suspicious characters or command patterns
• Deploy web application firewall (WAF) rules to block requests with shell metacharacters in form parameters
• Monitor authentication logs for brute force attempts or successful logins from unusual source IPs
• Analyze network traffic for unexpected outbound connections from IoT devices

Monitoring Recommendations

• Enable logging on the router management interface and forward logs to a centralized SIEM for analysis
• Implement network segmentation to isolate IoT devices and monitor inter-segment traffic
• Establish baseline network behavior for Tenda devices and alert on deviations
• Regularly audit device configurations and check for unauthorized changes

How to Mitigate CVE-2026-1690

Immediate Actions Required

• Change default administrative credentials on all Tenda HG10, HG7, and HG9 devices immediately
• Restrict access to the device management interface to trusted IP addresses only
• Disable remote management if not required for operational purposes
• Place affected devices behind a firewall that blocks access to port 80/443 from untrusted networks
• Monitor affected devices for signs of compromise while awaiting a vendor patch

Patch Information

At the time of publication, no official patch has been released by Tenda for this vulnerability. Organizations should monitor the Tenda official website for security advisories and firmware updates. Additional technical details are tracked in VulDB #343484.

Workarounds

• Implement strict access control lists (ACLs) to limit management interface access to specific trusted IP addresses
• Deploy network-level filtering to block requests containing command injection patterns to the affected endpoint
• Consider replacing affected devices with alternatives from vendors with better security patch response times
• If the device must remain in production, use an upstream firewall or reverse proxy to filter malicious requests

# Example iptables rule to restrict management interface access
iptables -A INPUT -p tcp --dport 80 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP