CVE-2024-33215: Tenda FH1206 Buffer Overflow Vulnerability

CVE-2024-33215 Overview

CVE-2024-33215 is a stack-based buffer overflow [CWE-121] in the Tenda FH1206 router running firmware version V1.2.0.8(8155)_EN. The flaw resides in the fromAddressNat handler reachable through the ip/goform/addressNat endpoint. An unauthenticated remote attacker can trigger the overflow by supplying a crafted mitInterface parameter. Successful exploitation can corrupt the stack and lead to arbitrary code execution on the device, granting full control of the affected router.

Critical Impact

Unauthenticated remote attackers can overflow the stack through the mitInterface parameter and gain code execution on the FH1206 router, compromising the confidentiality, integrity, and availability of the network perimeter.

Affected Products

• Tenda FH1206 hardware device
• Tenda FH1206 firmware version V1.2.0.8(8155)_EN
• Deployments exposing the ip/goform/addressNat web management endpoint

Discovery Timeline

• 2024-04-23 - CVE-2024-33215 published to the National Vulnerability Database
• 2025-03-17 - Last updated in the NVD database

Technical Details for CVE-2024-33215

Vulnerability Analysis

The vulnerability is a stack-based buffer overflow [CWE-121] in the HTTP handler that processes NAT address configuration requests on the Tenda FH1206. The fromAddressNat function reads attacker-controlled data from the mitInterface HTTP parameter and writes it into a fixed-size stack buffer without enforcing length checks. Because the router exposes this endpoint through the web administration interface, an attacker reachable over the network can deliver an oversized value and corrupt adjacent stack memory, including the saved return address.

The attack requires no authentication, no user interaction, and only network access to the device's management interface. Routers exposing the web interface to the WAN or to untrusted LAN segments are directly reachable. Successful exploitation yields code execution in the context of the embedded web server, which typically runs with elevated privileges on consumer-grade routers.

Root Cause

The root cause is missing bounds validation on the mitInterface request parameter before it is copied into a stack-allocated buffer inside the fromAddressNat handler. The firmware trusts the length of the user-supplied value, allowing the copy operation to write past the buffer boundary.

Attack Vector

An attacker sends a crafted HTTP request to /goform/addressNat containing an overlong mitInterface parameter. The malformed request overwrites stack data, including control flow metadata, enabling redirection of execution. Technical details of the request structure are documented in the Notion Document on NAT.

No verified public exploit code is available for this CVE. The vulnerability mechanism follows the standard MIPS/ARM embedded router stack-overflow pattern: an unchecked strcpy-style copy of a long query or POST parameter into a small local buffer overwrites the saved return address on the stack.

Detection Methods for CVE-2024-33215

Indicators of Compromise

• HTTP POST or GET requests to /goform/addressNat containing unusually long mitInterface parameter values
• Unexpected reboots, watchdog resets, or web server crashes on FH1206 devices following inbound HTTP traffic
• Outbound connections from the router to unknown hosts, indicating possible post-exploitation implant activity

Detection Strategies

• Inspect web server and management interface logs for malformed requests targeting addressNat with oversized parameters
• Deploy network IDS signatures that flag HTTP requests to goform/addressNat where mitInterface exceeds expected length
• Correlate router crash events with preceding inbound HTTP traffic on the management interface

Monitoring Recommendations

• Monitor management plane traffic to Tenda devices and alert on requests from non-administrative source addresses
• Track firmware integrity and configuration drift on FH1206 units to detect persistence after compromise
• Aggregate router syslog output into a centralized logging platform for retrospective analysis

How to Mitigate CVE-2024-33215

Immediate Actions Required

• Restrict access to the FH1206 web management interface so that only trusted administrative hosts can reach /goform/ endpoints
• Disable remote WAN-side administration on all FH1206 deployments
• Inventory all Tenda FH1206 devices running firmware V1.2.0.8(8155)_EN and prioritize them for replacement or isolation

Patch Information

No vendor advisory or patched firmware release has been published in the references associated with CVE-2024-33215. Operators should monitor the Tenda support site for an updated firmware release addressing the fromAddressNat handler. Until a fixed firmware is available, treat affected devices as exposed and apply compensating network controls.

Workarounds

• Place FH1206 routers behind an upstream firewall that blocks unsolicited inbound HTTP and HTTPS traffic to the device
• Segment the management VLAN so that only authorized workstations can reach the router's web interface
• Replace end-of-support or unpatched FH1206 units with a currently supported model that receives security updates

# Example: block external access to the Tenda web admin interface on an upstream Linux gateway
iptables -A FORWARD -p tcp -d <FH1206_IP> --dport 80  -m conntrack --ctstate NEW -j DROP
iptables -A FORWARD -p tcp -d <FH1206_IP> --dport 443 -m conntrack --ctstate NEW -j DROP

# Allow only the administrative workstation
iptables -I FORWARD -p tcp -s <ADMIN_IP> -d <FH1206_IP> --dport 80  -j ACCEPT
iptables -I FORWARD -p tcp -s <ADMIN_IP> -d <FH1206_IP> --dport 443 -j ACCEPT