CVE-2026-1689: Tenda HG10 Firmware RCE Vulnerability

CVE-2026-1689 Overview

CVE-2026-1689 is a command injection vulnerability in the Tenda HG10 router running firmware US_HG7_HG9_HG10re_300001138_en_xpon. The flaw resides in the checkUserFromLanOrWan function within /boaform/admin/formLogin, part of the device's login interface. Attackers can manipulate the Host HTTP header argument to inject operating system commands processed by the underlying shell. The attack is remotely exploitable without authentication, and a public proof-of-concept has been disclosed through VulDB and a GitHub repository.

Critical Impact
Unauthenticated remote attackers can inject arbitrary commands through the Host header on the login endpoint, potentially gaining control of the affected Tenda HG10 router.

Affected Products

Tenda HG10 router (hardware)
Tenda HG10 firmware US_HG7_HG9_HG10re_300001138_en_xpon
Login interface component at /boaform/admin/formLogin

Discovery Timeline

2026-01-30 - CVE-2026-1689 published to the National Vulnerability Database
2026-04-29 - Last updated in NVD database

Technical Details for CVE-2026-1689

Vulnerability Analysis

The vulnerability is classified under CWE-74 (Improper Neutralization of Special Elements in Output Used by a Downstream Component). The affected checkUserFromLanOrWan function processes incoming login requests at /boaform/admin/formLogin and incorporates the value of the HTTP Host header into a downstream command without proper sanitization.

Because the injection point is reachable before authentication, attackers do not need valid credentials. Successful exploitation allows arbitrary command execution in the context of the web server process, which on consumer routers typically runs as root. The exploit code is publicly available, increasing the likelihood of opportunistic attacks against exposed devices.

Root Cause

The root cause is unsanitized use of the user-controlled Host header value within the checkUserFromLanOrWan routine. The header content flows into a shell command construction path without input validation, escaping, or argument separation, allowing shell metacharacters to break command boundaries.

Attack Vector

The attack vector is network-based and requires no privileges or user interaction. An attacker sends a crafted HTTP request to the /boaform/admin/formLogin endpoint with shell metacharacters embedded in the Host header. The Tenda HG10 device parses the request, passes the malicious header into the vulnerable function, and the operating system executes the injected commands. Public proof-of-concept details are available in the GitHub PoC Repository and the VulDB entry #343483.

Detection Methods for CVE-2026-1689

Indicators of Compromise

HTTP requests to /boaform/admin/formLogin containing shell metacharacters (;, |, &, backticks, $()) within the Host header.
Unexpected outbound connections originating from the router after receiving login requests, which may indicate command execution success.
New or modified accounts, configuration changes, or unfamiliar processes running on the Tenda HG10 device.
Repeated probe traffic from the same external IP targeting /boaform/admin/formLogin across multiple devices.

Detection Strategies

Inspect HTTP traffic to administrative endpoints on Tenda HG10 routers and alert on non-RFC-compliant Host header values containing shell special characters.
Deploy network IDS rules that match request patterns specific to the public PoC against /boaform/admin/formLogin.
Correlate router-originated DNS queries or outbound HTTP/TCP sessions with prior inbound administrative requests to identify post-exploitation callbacks.

Monitoring Recommendations

Forward router and gateway logs to a centralized SIEM and monitor for anomalous administrative requests from untrusted networks.
Track ingress traffic targeting embedded /boaform/ URI paths, which are common to several Tenda router firmware families.
Periodically scan internal and external network ranges to identify exposed Tenda HG10 management interfaces.

How to Mitigate CVE-2026-1689

Immediate Actions Required

Remove WAN-side exposure of the Tenda HG10 administrative web interface and restrict access to trusted management VLANs only.
Place affected devices behind a firewall or upstream gateway that filters requests to /boaform/admin/formLogin from untrusted sources.
Inspect router configurations and logs for indicators of prior exploitation, including unauthorized account or DNS changes.

Patch Information

At the time of publication, no vendor advisory or firmware fix has been listed in the CVE references. Administrators should monitor the Tenda official website for updated firmware releases addressing the checkUserFromLanOrWan command injection.

Workarounds

Disable remote (WAN) management on the Tenda HG10 device until a patched firmware version is available.
Apply ACLs on upstream network equipment to block external access to TCP ports hosting the router web interface.
Replace affected devices with supported, actively maintained hardware if vendor patches are not released in a reasonable timeframe.

bash

# Example: block external access to the router admin interface on an upstream Linux gateway
iptables -A FORWARD -p tcp -d <router_ip> --dport 80 -i <wan_iface> -j DROP
iptables -A FORWARD -p tcp -d <router_ip> --dport 443 -i <wan_iface> -j DROP