CVE-2026-3167: Tenda F453 Buffer Overflow Vulnerability

CVE-2026-3167 Overview

A buffer overflow vulnerability has been discovered in Tenda F453 firmware version 1.0.0.3. The vulnerability exists in the formWebTypeLibrary function within the /goform/webtypelibrary endpoint of the httpd web service component. By manipulating the webSiteId argument, an attacker can trigger a buffer overflow condition. This vulnerability can be exploited remotely over the network and a public exploit has been disclosed.

Critical Impact

Remote attackers with low-level privileges can exploit this buffer overflow to achieve high impact on confidentiality, integrity, and availability of the affected Tenda F453 router, potentially leading to complete device compromise.

Affected Products

• Tenda F453 Firmware version 1.0.0.3
• Tenda F453 Hardware

Discovery Timeline

• 2026-02-25 - CVE-2026-3167 published to NVD
• 2026-02-25 - Last updated in NVD database

Technical Details for CVE-2026-3167

Vulnerability Analysis

This vulnerability is classified under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer). The flaw resides in the formWebTypeLibrary function, which handles web requests to the /goform/webtypelibrary endpoint on the Tenda F453's embedded HTTP daemon (httpd). The function fails to properly validate the length or content of the webSiteId parameter before processing it, leading to a buffer overflow condition.

When a specially crafted request is sent to the vulnerable endpoint with an oversized or malformed webSiteId argument, the function writes data beyond the allocated buffer boundaries. This memory corruption can overwrite adjacent memory regions, potentially including return addresses, function pointers, or other critical data structures.

Root Cause

The root cause of this vulnerability is insufficient input validation and boundary checking in the formWebTypeLibrary function. The function accepts user-supplied data via the webSiteId parameter without verifying that the input length does not exceed the allocated buffer size. This is a common vulnerability pattern in embedded device firmware where memory-safe programming practices may not be consistently applied.

Attack Vector

The attack is network-based and requires low-privileged access to the device's web management interface. An attacker can exploit this vulnerability by sending a specially crafted HTTP request to the /goform/webtypelibrary endpoint with a malicious webSiteId parameter value designed to overflow the target buffer.

The exploitation flow typically involves:

1. Identifying a vulnerable Tenda F453 device running firmware version 1.0.0.3
2. Crafting an HTTP request with an oversized or specially formatted webSiteId parameter
3. Sending the malicious request to the /goform/webtypelibrary endpoint
4. The overflow corrupts memory, potentially allowing code execution or causing denial of service

For technical details on the vulnerability mechanism, refer to the GitHub Vulnerability Database Entry.

Detection Methods for CVE-2026-3167

Indicators of Compromise

• Unusual HTTP POST requests targeting /goform/webtypelibrary with abnormally large webSiteId parameter values
• Unexpected httpd service crashes or restarts on Tenda F453 devices
• Anomalous network traffic patterns to the router's web management interface from untrusted sources
• Evidence of unauthorized configuration changes or persistent access to the device

Detection Strategies

• Implement network intrusion detection rules to monitor HTTP traffic destined for Tenda F453 management interfaces, specifically looking for requests to /goform/webtypelibrary with suspicious payload sizes
• Deploy web application firewall (WAF) rules to filter requests with oversized parameters targeting the vulnerable endpoint
• Configure logging on network devices to capture all access attempts to router management interfaces

Monitoring Recommendations

• Monitor network traffic for unusual patterns targeting port 80/443 on Tenda router management interfaces
• Implement alerting for repeated requests to /goform/webtypelibrary endpoints across the network
• Regularly audit device logs for signs of exploitation attempts or service instability

How to Mitigate CVE-2026-3167

Immediate Actions Required

• Restrict access to the Tenda F453 web management interface to trusted IP addresses only
• Disable remote management access if not required for operations
• Place affected devices behind a firewall and block external access to management ports
• Monitor for firmware updates from Tenda that address this vulnerability

Patch Information

As of the last NVD update on 2026-02-25, no official patch has been released by Tenda to address this vulnerability. Organizations should monitor the Tenda Official Website for security advisories and firmware updates. Additional vulnerability details are available via VulDB #347674.

Workarounds

• Implement network segmentation to isolate Tenda F453 devices from untrusted network segments
• Configure firewall rules to block access to the /goform/webtypelibrary endpoint from external networks
• Consider replacing vulnerable devices with alternative hardware if patches are not forthcoming
• Enable access control lists (ACLs) to limit management interface access to specific administrator IP addresses

# Example firewall rule to restrict access to Tenda management interface
# Block external access to the vulnerable endpoint
iptables -A FORWARD -d <TENDA_DEVICE_IP> -p tcp --dport 80 -m string --string "/goform/webtypelibrary" --algo bm -j DROP

# Allow management access only from trusted admin subnet
iptables -A INPUT -s <ADMIN_SUBNET> -d <TENDA_DEVICE_IP> -p tcp --dport 80 -j ACCEPT
iptables -A INPUT -d <TENDA_DEVICE_IP> -p tcp --dport 80 -j DROP