CVE-2024-51313: Tenda TX9 Buffer Overflow Vulnerability

CVE-2024-51313 Overview

CVE-2024-51313 is a stack overflow vulnerability in the Tenda TX9 router firmware version V22.03.02.20. The flaw resides in the sub_42EA38 function that handles requests to the /goform/SetVirtualServerCfg endpoint. Unauthenticated remote attackers can send crafted HTTP requests to this endpoint to overflow a fixed-size stack buffer. Successful exploitation can lead to arbitrary code execution on the device or a denial-of-service condition. The vulnerability is classified under CWE-121: Stack-based Buffer Overflow and affects the web management interface exposed by the router.

Critical Impact
Unauthenticated attackers on the network can trigger arbitrary code execution or crash the router by sending crafted requests to /goform/SetVirtualServerCfg.

Affected Products

Tenda TX9 router firmware version V22.03.02.20
Web management interface handler /goform/SetVirtualServerCfg
Vulnerable function sub_42EA38 within the firmware httpd binary

Discovery Timeline

2026-07-20 - CVE-2024-51313 published to the National Vulnerability Database (NVD)
2026-07-21 - Last updated in NVD database

Technical Details for CVE-2024-51313

Vulnerability Analysis

The Tenda TX9 web server processes virtual server configuration requests through the /goform/SetVirtualServerCfg handler. Inside the sub_42EA38 function, user-supplied parameters from the HTTP request are copied into a fixed-size stack buffer without validating the input length. When the attacker submits an oversized parameter value, the copy operation writes beyond the buffer boundary and corrupts adjacent stack memory, including saved return addresses.

Because the endpoint is reachable over the network and requires no authentication or user interaction, the attack surface is exposed to any client that can reach the router's management interface. Devices that expose the web interface to the WAN side are at elevated risk, but LAN-side exploitation is also viable from compromised internal hosts.

Root Cause

The root cause is missing bounds checking on attacker-controlled input during a stack buffer copy operation inside sub_42EA38. The handler trusts the length of parameters supplied in the POST body to /goform/SetVirtualServerCfg and copies them directly into a local stack buffer. This is a classic [CWE-121] stack-based buffer overflow pattern common in embedded MIPS/ARM router firmware.

Attack Vector

An attacker crafts an HTTP POST request to /goform/SetVirtualServerCfg on the router's web management port. The request includes an oversized value for one of the virtual server configuration parameters processed by sub_42EA38. The overflow overwrites the saved return address on the stack, redirecting execution to attacker-controlled data. On embedded Linux devices with limited exploit mitigations, this typically results in code execution with root privileges or a crash of the httpd process.

The vulnerability mechanism is documented in the public Gitee IoT Vulnerability Documentation.

Detection Methods for CVE-2024-51313

Indicators of Compromise

HTTP POST requests to /goform/SetVirtualServerCfg containing unusually long parameter values or non-printable byte sequences
Unexpected restarts or crashes of the router's httpd process visible through connectivity interruptions on the management interface
Outbound connections from the router to unknown hosts, suggesting post-exploitation callback activity

Detection Strategies

Deploy network intrusion detection signatures that inspect HTTP request bodies destined for /goform/SetVirtualServerCfg and flag parameter lengths exceeding expected limits
Log and review all administrative HTTP requests to the router's web interface, correlating source IPs against known management workstations
Monitor router uptime and process health to catch abnormal restarts that may indicate exploitation attempts

Monitoring Recommendations

Enable syslog forwarding from the router to a centralized log platform to capture web management activity
Alert on any HTTP traffic to router management endpoints originating from the WAN interface
Establish a baseline of normal /goform/* request patterns and alert on deviations in request size or frequency

How to Mitigate CVE-2024-51313

Immediate Actions Required

Restrict access to the router's web management interface to trusted LAN hosts only and disable remote WAN management
Apply the firmware update supplied by Tenda through the Tenda Security Patch Download portal
Audit virtual server (port forwarding) rules and remove any entries that were not created by authorized administrators

Patch Information

Tenda has published updated firmware for the TX9 device on its official download portal. Administrators should verify the running firmware version against V22.03.02.20 and upgrade to the latest available release. Refer to the Tenda Security Patch Download page for the appropriate firmware image and installation instructions.

Workarounds

Disable the remote web management feature so that /goform/SetVirtualServerCfg is not exposed to untrusted networks
Place the router's management interface behind a segmented VLAN accessible only to administrator workstations
Use an upstream firewall to block inbound access to the router's HTTP management port from the internet

bash

# Example: block inbound access to router HTTP management port from WAN using an upstream firewall
iptables -A FORWARD -p tcp -d <router_wan_ip> --dport 80 -j DROP
iptables -A FORWARD -p tcp -d <router_wan_ip> --dport 443 -j DROP