CVE-2026-3399: Tenda F453 Buffer Overflow Vulnerability

CVE-2026-3399 Overview

A buffer overflow vulnerability has been identified in Tenda F453 firmware version 1.0.0.3. This vulnerability affects the fromGstDhcpSetSer function within the /goform/GstDhcpSetSer endpoint of the httpd component. By manipulating the dips argument, a remote attacker can trigger a buffer overflow condition that may lead to arbitrary code execution or denial of service on the affected device.

Critical Impact

Remote attackers can exploit this buffer overflow vulnerability to potentially execute arbitrary code or cause system instability on Tenda F453 routers running firmware version 1.0.0.3.

Affected Products

• Tenda F453 Firmware version 1.0.0.3
• Tenda F453 Hardware

Discovery Timeline

• 2026-03-01 - CVE-2026-3399 published to NVD
• 2026-03-03 - Last updated in NVD database

Technical Details for CVE-2026-3399

Vulnerability Analysis

This vulnerability exists within the web management interface of the Tenda F453 router. The httpd service running on the device contains a vulnerable function fromGstDhcpSetSer that processes DHCP server configuration requests. When handling the dips parameter, the function fails to properly validate the length of user-supplied input before copying it into a fixed-size buffer on the stack or heap.

The lack of bounds checking allows an authenticated attacker with low privileges to send a specially crafted HTTP request containing an oversized value for the dips argument. This overflow can corrupt adjacent memory regions, potentially overwriting critical data structures, return addresses, or function pointers.

Root Cause

The root cause of this vulnerability is classified as CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer). The fromGstDhcpSetSer function does not implement adequate input length validation when processing the dips parameter. This allows user-controlled data to exceed the allocated buffer boundaries, leading to memory corruption.

Attack Vector

The vulnerability is exploitable remotely over the network. An attacker with low-privilege access to the router's web interface can craft a malicious HTTP POST request to /goform/GstDhcpSetSer containing an oversized dips parameter value. The attack does not require user interaction and can be executed directly against the httpd service.

The exploitation mechanism involves:

1. Authenticating to the Tenda F453 web management interface
2. Sending a crafted HTTP POST request to /goform/GstDhcpSetSer
3. Including an oversized payload in the dips parameter to trigger the buffer overflow
4. Potentially gaining code execution or causing a denial of service condition

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

Detection Methods for CVE-2026-3399

Indicators of Compromise

• Unusual HTTP POST requests to /goform/GstDhcpSetSer with abnormally large dips parameter values
• Unexpected httpd service crashes or router reboots
• Anomalous network traffic patterns originating from the router's management interface
• Evidence of unauthorized configuration changes to DHCP server settings

Detection Strategies

• Monitor HTTP traffic to the router's web management interface for requests containing oversized parameters
• Implement intrusion detection rules to flag POST requests to /goform/GstDhcpSetSer with dips values exceeding expected lengths
• Configure network monitoring to detect repeated connection attempts to the httpd service that may indicate exploitation attempts
• Review router logs for unexpected service restarts or error conditions

Monitoring Recommendations

• Restrict access to the router's web management interface to trusted networks only
• Enable logging on the Tenda F453 device if available and forward logs to a centralized SIEM
• Deploy network-based monitoring solutions to capture traffic to and from the device management ports
• Establish baseline behavior patterns for legitimate DHCP configuration requests to identify anomalies

How to Mitigate CVE-2026-3399

Immediate Actions Required

• Restrict access to the Tenda F453 web management interface from untrusted networks
• Implement network segmentation to isolate the affected device from critical infrastructure
• Disable remote management access if not required for operations
• Monitor the Tenda Official Website for security updates and firmware patches

Patch Information

At the time of publication, no official patch has been released by Tenda for this vulnerability. Organizations should monitor vendor communications for firmware updates that address this buffer overflow issue. Additional technical information can be found in the VulDB Entry #348294.

Workarounds

• Configure firewall rules to block external access to the router's management interface (typically port 80 or 443)
• Use ACLs to restrict management access to specific trusted IP addresses only
• Consider deploying a network-based web application firewall to filter malicious requests
• If possible, disable the vulnerable DHCP server configuration functionality until a patch is available
• Implement network monitoring to detect and alert on potential exploitation attempts

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