CVE-2026-7097: Tenda F456 Buffer Overflow Vulnerability

CVE-2026-7097 Overview

A buffer overflow vulnerability has been identified in Tenda F456 firmware version 1.0.0.5. This issue affects the function fromwebExcptypemanFilter of the file /goform/webExcptypemanFilter within the httpd component. Manipulation of the page argument causes a buffer overflow condition that can be exploited remotely by authenticated attackers. The exploit has been made publicly available, increasing the risk of active exploitation against vulnerable devices.

Critical Impact

Remote attackers with low privileges can exploit this buffer overflow to potentially achieve code execution, compromise device integrity, and gain unauthorized control over the affected Tenda F456 router, impacting network security.

Affected Products

• Tenda F456 Firmware version 1.0.0.5
• Tenda F456 Hardware

Discovery Timeline

• 2026-04-27 - CVE CVE-2026-7097 published to NVD
• 2026-04-30 - Last updated in NVD database

Technical Details for CVE-2026-7097

Vulnerability Analysis

This vulnerability exists in the httpd web service running on Tenda F456 routers. The fromwebExcptypemanFilter function, accessible via the /goform/webExcptypemanFilter endpoint, fails to properly validate the length of user-supplied input provided through the page parameter. When an attacker sends a crafted request with an oversized value for the page argument, the function copies this data into a fixed-size buffer without adequate bounds checking, resulting in a classic buffer overflow condition (CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer).

The vulnerability can be triggered remotely over the network, requiring only low-level authentication to access the vulnerable endpoint. Successful exploitation could allow an attacker to overwrite adjacent memory regions, potentially corrupting critical data structures, hijacking program execution flow, or causing denial of service conditions.

Root Cause

The root cause of CVE-2026-7097 is improper input validation in the fromwebExcptypemanFilter function within the httpd component. The function does not perform adequate boundary checks when processing the page parameter, allowing user-supplied data to exceed the allocated buffer size. This is a common vulnerability pattern in embedded device firmware where memory-safe programming practices are not consistently applied, particularly in C/C++ implementations handling HTTP form data.

Attack Vector

The attack vector is network-based, targeting the web management interface of the Tenda F456 router. An attacker with low-level authentication to the device's web interface can craft a malicious HTTP POST request to the /goform/webExcptypemanFilter endpoint. By supplying an excessively long string in the page parameter, the attacker triggers the buffer overflow condition.

The exploitation process involves:

1. Accessing the router's web management interface
2. Authenticating with valid credentials (even low-privilege accounts)
3. Sending a crafted POST request to /goform/webExcptypemanFilter
4. Overflowing the buffer via the page parameter
5. Potentially achieving code execution or denial of service

Additional technical details are available in the GitHub README for this vulnerability and the VulDB vulnerability entry.

Detection Methods for CVE-2026-7097

Indicators of Compromise

• Unusual HTTP POST requests to /goform/webExcptypemanFilter with abnormally long page parameter values
• Unexpected crashes or restarts of the httpd service on Tenda F456 devices
• Anomalous memory consumption patterns on affected routers
• Unauthorized configuration changes or suspicious administrative activity

Detection Strategies

• Monitor network traffic for HTTP requests targeting /goform/webExcptypemanFilter with oversized parameters
• Implement intrusion detection rules to alert on POST requests containing excessively long strings in form data
• Deploy web application firewall (WAF) rules to filter requests with abnormal parameter lengths
• Review httpd service logs for crash events or error patterns indicative of memory corruption

Monitoring Recommendations

• Enable comprehensive logging on the Tenda F456 web management interface
• Configure network monitoring to capture traffic to and from router management ports
• Establish baseline behavior for administrative access patterns and alert on deviations
• Consider network segmentation to limit exposure of router management interfaces

How to Mitigate CVE-2026-7097

Immediate Actions Required

• Restrict access to the Tenda F456 web management interface to trusted networks only
• Disable remote management features if not required
• Implement strong, unique credentials for router administration
• Monitor for signs of compromise on affected devices
• Consider network segmentation to isolate management interfaces from untrusted networks

Patch Information

At the time of publication, no vendor patch has been confirmed for CVE-2026-7097. Organizations should monitor the Tenda official website for firmware updates addressing this vulnerability. Until a patch is available, implement the workarounds and mitigations described below to reduce exposure.

Workarounds

• Disable remote web management access and allow only local administration
• Implement firewall rules to restrict access to the router's management interface (typically port 80/443)
• Use a VPN or bastion host for administrative access to reduce attack surface
• Consider replacing affected devices with alternative hardware if updates are not forthcoming

# Example firewall rule to restrict management access (adjust for your environment)
# Block external access to router 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