CVE-2026-3398: Tenda F453 Buffer Overflow Vulnerability

CVE-2026-3398 Overview

A buffer overflow vulnerability has been identified in the Tenda F453 wireless router running firmware version 1.0.0.3. The vulnerability exists in the fromAdvSetWan function within the /goform/AdvSetWan endpoint of the httpd web service component. Attackers can exploit this vulnerability by manipulating the wanmode or PPPOEPassword arguments to trigger a buffer overflow condition. This vulnerability can be exploited remotely over the network, and exploit details have been publicly disclosed.

Critical Impact

Remote attackers with low-level privileges can exploit this buffer overflow to potentially execute arbitrary code, compromise device integrity, and gain full control of affected Tenda F453 routers.

Affected Products

• Tenda F453 Firmware version 1.0.0.3
• Tenda F453 Hardware

Discovery Timeline

• 2026-03-01 - CVE-2026-3398 published to NVD
• 2026-03-03 - Last updated in NVD database

Technical Details for CVE-2026-3398

Vulnerability Analysis

This buffer overflow vulnerability (CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer) affects the fromAdvSetWan function in the Tenda F453 router's httpd web server. The vulnerable function processes WAN configuration requests through the /goform/AdvSetWan endpoint without proper bounds checking on user-supplied input.

When an attacker sends a crafted request containing oversized data in the wanmode or PPPOEPassword parameters, the function fails to validate input length before copying the data into fixed-size memory buffers. This allows memory corruption beyond the intended buffer boundaries, potentially overwriting adjacent memory structures including return addresses and function pointers.

The network-accessible nature of this vulnerability is particularly concerning for embedded devices like routers, which often serve as perimeter security devices. Successful exploitation could allow attackers to execute arbitrary code with the privileges of the httpd process, typically running as root on embedded Linux systems.

Root Cause

The root cause of this vulnerability is improper input validation in the fromAdvSetWan function. The function accepts user-controlled input from the wanmode and PPPOEPassword HTTP parameters and copies this data into fixed-size stack or heap buffers without verifying that the input length does not exceed the allocated buffer size. This classic buffer overflow pattern is common in embedded device firmware where memory-safe programming practices may not be consistently applied.

Attack Vector

The attack can be executed remotely over the network by any authenticated user with access to the router's web management interface. An attacker constructs a malicious HTTP POST request to the /goform/AdvSetWan endpoint containing an oversized value in either the wanmode or PPPOEPassword parameter. When the vulnerable fromAdvSetWan function processes this request, the buffer overflow occurs, potentially allowing the attacker to hijack program execution flow.

The vulnerability is exploitable with low-privilege access and requires no user interaction, making it particularly dangerous in environments where attackers may have access to the network segment where the router's management interface is exposed.

For detailed technical analysis and proof-of-concept information, see the GitHub Vulnerability Report.

Detection Methods for CVE-2026-3398

Indicators of Compromise

• Unusual or malformed HTTP POST requests to /goform/AdvSetWan containing abnormally long parameter values
• Unexpected httpd process crashes or restarts on Tenda F453 devices
• Anomalous network traffic patterns indicating exploitation attempts against the router management interface
• Evidence of unauthorized configuration changes or persistent backdoor installation on the device

Detection Strategies

• Implement network intrusion detection rules to identify HTTP requests to /goform/AdvSetWan with oversized wanmode or PPPOEPassword parameters
• Monitor web server logs for repeated requests to the vulnerable endpoint with unusually large payload sizes
• Deploy application-layer firewall rules to enforce maximum parameter lengths for WAN configuration requests
• Utilize SentinelOne Singularity for network visibility and anomaly detection on IoT device traffic

Monitoring Recommendations

• Enable verbose logging on the Tenda F453 if available and monitor for httpd service anomalies
• Implement network segmentation to isolate router management interfaces from untrusted networks
• Deploy continuous vulnerability scanning to identify unpatched Tenda devices in your environment
• Establish baseline behavior monitoring for IoT and network infrastructure devices

How to Mitigate CVE-2026-3398

Immediate Actions Required

• Restrict access to the router's web management interface to trusted IP addresses only
• Disable remote management functionality if not required for operations
• Place the Tenda F453 behind a firewall that filters access to the /goform/AdvSetWan endpoint
• Monitor for vendor firmware updates from Tenda and apply patches as soon as available
• Consider replacing affected devices with alternative hardware if no patch is forthcoming

Patch Information

At the time of publication, no official patch has been released by Tenda for this vulnerability. Organizations should monitor the Tenda Official Website for security updates. Additional vulnerability details are available through VulDB #348293.

Workarounds

• Implement access control lists (ACLs) to restrict management interface access to specific trusted IP addresses
• Disable the web management interface entirely and use console access for device administration when possible
• Deploy network-level filtering to block or rate-limit requests to vulnerable endpoints
• Consider network segmentation to isolate vulnerable IoT devices from critical network segments

# Example: iptables rule to restrict access to router management interface
# Apply on upstream firewall or router if external management access is required

# Allow management access only from trusted admin subnet
iptables -A FORWARD -d <ROUTER_IP> -p tcp --dport 80 -s <TRUSTED_ADMIN_SUBNET> -j ACCEPT
iptables -A FORWARD -d <ROUTER_IP> -p tcp --dport 80 -j DROP

# Alternative: Block specific vulnerable endpoint at reverse proxy or WAF
# Block requests to /goform/AdvSetWan with oversized parameters