CVE-2026-3726: Tenda F453 Buffer Overflow Vulnerability

CVE-2026-3726 Overview

A stack-based buffer overflow vulnerability has been discovered in Tenda F453 firmware version 1.0.0.3. This vulnerability affects the function fromwebExcptypemanFilter located in the file /goform/webExcptypemanFilter. The manipulation of the page argument leads to a stack-based buffer overflow condition. This vulnerability can be exploited remotely by an authenticated attacker to execute arbitrary code on the affected device.

Critical Impact

This buffer overflow vulnerability allows remote attackers to potentially execute arbitrary code on Tenda F453 routers, compromising network security and enabling further attacks on connected devices.

Affected Products

• Tenda F453 Firmware version 1.0.0.3
• Tenda F453 hardware devices running vulnerable firmware

Discovery Timeline

• 2026-03-08 - CVE-2026-3726 published to NVD
• 2026-03-09 - Last updated in NVD database

Technical Details for CVE-2026-3726

Vulnerability Analysis

This vulnerability is classified under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer). The fromwebExcptypemanFilter function in the Tenda F453 firmware fails to properly validate the length of user-supplied input provided through the page parameter. When a maliciously crafted request is sent to the /goform/webExcptypemanFilter endpoint, the input data overflows the allocated stack buffer, potentially overwriting critical stack data including return addresses.

The vulnerability is accessible over the network and requires low-privilege authentication to exploit. Once triggered, an attacker can achieve high impact on confidentiality, integrity, and availability of the affected device.

Root Cause

The root cause of this vulnerability stems from insufficient input validation in the fromwebExcptypemanFilter function. The function does not properly validate the size of user-supplied input before copying it into a fixed-size stack buffer. This classic buffer overflow pattern allows attackers to write beyond the boundaries of the allocated memory space, corrupting adjacent stack memory.

Attack Vector

The attack vector is network-based, allowing remote exploitation through the device's web management interface. An authenticated attacker can send a specially crafted HTTP request to the /goform/webExcptypemanFilter endpoint with an oversized page parameter value. The malicious payload would contain carefully constructed data designed to overwrite the return address on the stack, redirecting program execution to attacker-controlled code.

The vulnerability has been publicly disclosed, and technical details are available in external vulnerability documentation. Organizations should consider this a high-priority issue due to the public availability of vulnerability details.

Detection Methods for CVE-2026-3726

Indicators of Compromise

• Unusual HTTP requests to /goform/webExcptypemanFilter with abnormally large page parameter values
• Web server crash logs or unexpected device reboots indicating exploitation attempts
• Anomalous outbound network connections from the Tenda F453 device after successful exploitation

Detection Strategies

• Monitor network traffic for HTTP POST requests to /goform/webExcptypemanFilter containing oversized parameter values
• Implement intrusion detection rules to flag requests with page parameters exceeding expected length thresholds
• Enable logging on network perimeter devices to capture suspicious requests targeting Tenda device management interfaces

Monitoring Recommendations

• Conduct regular firmware version audits to identify devices running vulnerable version 1.0.0.3
• Deploy network segmentation to isolate IoT devices like routers from critical network assets
• Implement continuous monitoring for abnormal traffic patterns to and from Tenda devices

How to Mitigate CVE-2026-3726

Immediate Actions Required

• Restrict access to the Tenda F453 web management interface to trusted IP addresses only
• Disable remote management features if not required for operations
• Implement network segmentation to limit exposure of vulnerable devices
• Monitor for patch availability from Tenda and apply updates immediately when released

Patch Information

At the time of publication, no vendor patch has been publicly announced for this vulnerability. Organizations should monitor Tenda's official website for security updates. Additional technical information is available through VulDB.

Workarounds

• Configure firewall rules to block external access to the /goform/webExcptypemanFilter endpoint
• Implement strong authentication and limit administrative access to trusted network segments
• Consider replacing vulnerable devices with alternative hardware if patches are not released in a timely manner

# Example firewall rule to restrict access to management interface
# Block external access to the vulnerable endpoint
iptables -A INPUT -p tcp --dport 80 -d <router_ip> -j DROP
iptables -A INPUT -p tcp --dport 443 -d <router_ip> -j DROP
# Allow only trusted management subnet
iptables -A INPUT -p tcp --dport 80 -s 192.168.1.0/24 -d <router_ip> -j ACCEPT