CVE-2026-7102: Tenda F456 Firmware RCE Vulnerability

CVE-2026-7102 Overview

A command injection vulnerability has been identified in the Tenda F456 router firmware version 1.0.0.5. This vulnerability affects the FromWriteFacMac function within the /goform/WriteFacMac endpoint of the httpd component. Improper handling of the mac parameter allows attackers to inject and execute arbitrary commands on the affected device. The attack can be executed remotely over the network, and a proof-of-concept exploit has been made publicly available.

Critical Impact
Remote attackers with low-level privileges can exploit this command injection vulnerability to execute arbitrary commands on vulnerable Tenda F456 routers, potentially leading to complete device compromise.

Affected Products

Tenda F456 Firmware version 1.0.0.5
Tenda F456 Hardware Device

Discovery Timeline

2026-04-27 - CVE-2026-7102 published to NVD
2026-04-29 - Last updated in NVD database

Technical Details for CVE-2026-7102

Vulnerability Analysis

This command injection vulnerability (CWE-74) exists in the Tenda F456 router's web management interface. The vulnerable function FromWriteFacMac fails to properly sanitize user-supplied input in the mac parameter before incorporating it into system commands. This allows an authenticated attacker with network access to inject malicious commands that execute with the privileges of the httpd service, typically running as root on embedded devices.

The vulnerability is accessible remotely through the network, requires low privileges to exploit, and does not require user interaction. An attacker who successfully exploits this vulnerability can gain unauthorized access to the device's operating system, potentially allowing them to modify configurations, intercept network traffic, or pivot to other devices on the network.

Root Cause

The root cause is improper input validation (CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component). The FromWriteFacMac function in the httpd service does not adequately sanitize or validate the mac parameter before passing it to system command execution functions. This allows special characters and command separators to be processed as part of the command, enabling arbitrary command injection.

Attack Vector

The attack vector is network-based, targeting the /goform/WriteFacMac endpoint on the device's web management interface. An attacker with low-level authentication can craft a malicious HTTP request containing command injection payloads in the mac parameter.

The vulnerability exploitation involves sending a specially crafted request to the affected endpoint where the mac parameter contains shell metacharacters (such as semicolons, pipes, or backticks) followed by arbitrary commands. When the vulnerable function processes this input, the injected commands are executed on the underlying operating system.

Technical details and proof-of-concept information are available in the GitHub PoC Repository.

Detection Methods for CVE-2026-7102

Indicators of Compromise

Unusual HTTP POST requests to /goform/WriteFacMac containing shell metacharacters in the mac parameter
Unexpected processes or services spawned by the httpd process on affected devices
Abnormal outbound network connections from the router to external IP addresses
Configuration changes or new user accounts created without administrator authorization

Detection Strategies

Monitor web server logs for suspicious requests to /goform/WriteFacMac endpoints containing unusual characters or encoded payloads
Implement network intrusion detection rules to identify command injection patterns in HTTP traffic destined for Tenda devices
Deploy behavioral analysis to detect anomalous process creation or network activity originating from router devices

Monitoring Recommendations

Enable logging on affected Tenda devices and centralize log collection for analysis
Configure alerts for HTTP requests to vulnerable endpoints containing common command injection patterns such as ;, |, $(), or backticks
Monitor for unexpected DNS queries or outbound connections from network infrastructure devices

How to Mitigate CVE-2026-7102

Immediate Actions Required

Restrict network access to the router's web management interface to trusted IP addresses only
Implement network segmentation to isolate affected devices from critical infrastructure
Disable remote management access if not required for normal operations
Monitor affected devices for signs of compromise while awaiting vendor patch

Patch Information

At the time of this publication, no official patch has been released by Tenda for this vulnerability. Organizations should monitor the Tenda Official Website for firmware updates and security advisories. Additional vulnerability details are tracked at VulDB #359677.

Workarounds

Configure firewall rules to block external access to the router's management interface (typically port 80/443)
Use access control lists (ACLs) to limit management access to specific trusted IP addresses or management VLANs
Deploy a Web Application Firewall (WAF) in front of the management interface to filter malicious requests
Consider replacing affected devices with alternatives from vendors with better security response practices

bash

# Example firewall configuration to restrict management access
# Block external access to management interface
iptables -A INPUT -p tcp --dport 80 -s !192.168.1.0/24 -j DROP
iptables -A INPUT -p tcp --dport 443 -s !192.168.1.0/24 -j DROP