CVE-2026-3810 Overview
A stack-based buffer overflow vulnerability has been discovered in the Tenda FH1202 wireless router firmware version 1.2.0.14(408). This vulnerability affects the fromDhcpListClient function located in the /goform/DhcpListClient endpoint. Improper handling of the page argument allows an attacker to trigger a buffer overflow condition, potentially leading to remote code execution or denial of service.
Critical Impact
Remote attackers with low-level privileges can exploit this vulnerability over the network without user interaction to compromise device confidentiality, integrity, and availability. A proof-of-concept exploit has been publicly disclosed.
Affected Products
- Tenda FH1202 Firmware version 1.2.0.14(408)
- Tenda FH1202 Hardware Device
Discovery Timeline
- 2026-03-09 - CVE-2026-3810 published to NVD
- 2026-03-09 - Last updated in NVD database
Technical Details for CVE-2026-3810
Vulnerability Analysis
This firmware vulnerability resides in the DHCP client list management functionality of the Tenda FH1202 router. The fromDhcpListClient function processes user-supplied input from the page parameter without proper boundary validation. When an attacker sends a specially crafted request to the /goform/DhcpListClient endpoint with an oversized page argument, the function copies this data onto the stack without checking its length against the allocated buffer size.
The vulnerability is classified under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer), which encompasses memory safety issues that can lead to data corruption, crashes, or arbitrary code execution. Since the overflow occurs on the stack, an attacker may be able to overwrite return addresses or other critical stack data to redirect program execution.
Root Cause
The root cause stems from inadequate input validation in the fromDhcpListClient function. The firmware fails to verify the length of the page parameter before copying it into a fixed-size stack buffer. This lack of bounds checking is a common vulnerability pattern in embedded device firmware, where memory-safe programming practices may not be consistently applied. The function assumes the incoming parameter will fit within its allocated buffer space, creating an exploitable condition when this assumption is violated.
Attack Vector
The vulnerability is remotely exploitable over the network. An authenticated attacker with low-level privileges can craft a malicious HTTP request targeting the /goform/DhcpListClient endpoint with an oversized page parameter. The attack does not require user interaction and can be executed remotely against any exposed Tenda FH1202 device running the vulnerable firmware version. Successful exploitation could allow the attacker to execute arbitrary code with the privileges of the web server process, potentially achieving full device compromise.
The attack involves sending a crafted HTTP POST request to the vulnerable endpoint. The page parameter is manipulated to include a payload that exceeds the buffer size allocated on the stack. Technical details and proof-of-concept information are available through the GitHub PoC repository and VulDB vulnerability details.
Detection Methods for CVE-2026-3810
Indicators of Compromise
- Unusual or malformed HTTP requests targeting /goform/DhcpListClient with abnormally long page parameter values
- Unexpected router reboots or crashes indicating potential exploitation attempts
- Anomalous network traffic patterns originating from the router's management interface
Detection Strategies
- Monitor web server logs for requests to /goform/DhcpListClient containing unusually long parameter values
- Implement intrusion detection rules to flag HTTP requests with excessive payload sizes targeting Tenda router endpoints
- Deploy network-based anomaly detection to identify exploitation attempts against IoT devices
Monitoring Recommendations
- Enable logging on the router if supported and regularly review for suspicious access patterns
- Use network monitoring tools to detect traffic to and from the router's administrative ports
- Consider isolating IoT devices including routers on separate network segments with strict access controls
How to Mitigate CVE-2026-3810
Immediate Actions Required
- Restrict network access to the router's web management interface to trusted IP addresses only
- Disable remote management functionality if not required
- Place the affected device behind a firewall that can filter malicious requests
- Monitor for firmware updates from Tenda and apply patches when available
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. Users are advised to check for firmware updates regularly and apply them as soon as they become available.
Workarounds
- Disable remote administration access to the router's web interface
- Implement network segmentation to isolate the vulnerable device from untrusted networks
- Use firewall rules to block external access to the /goform/ endpoint
- Consider replacing the device with a router that receives regular security updates
# Example firewall rule to block external access to the vulnerable endpoint
# (Applies to upstream firewall protecting the Tenda device)
iptables -A FORWARD -d <ROUTER_IP> -p tcp --dport 80 -m string --string "/goform/DhcpListClient" --algo bm -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
