CVE-2026-7029: Tenda F456 Buffer Overflow Vulnerability

CVE-2026-7029 Overview

A buffer overflow vulnerability has been identified in Tenda F456 firmware version 1.0.0.5. The vulnerability exists in the fromaddressNat function within the /goform/addressNat endpoint. An attacker can exploit this vulnerability by manipulating the menufacturer/Go argument, leading to a buffer overflow condition. This vulnerability is remotely exploitable, and proof-of-concept exploit code has been made publicly available.

Critical Impact
Remote attackers can exploit this buffer overflow to potentially execute arbitrary code, compromise device integrity, or cause denial of service on affected Tenda F456 routers.

Affected Products

Tenda F456 Firmware version 1.0.0.5
Tenda F456 hardware devices running vulnerable firmware

Discovery Timeline

2026-04-26 - CVE-2026-7029 published to NVD
2026-04-30 - Last updated in NVD database

Technical Details for CVE-2026-7029

Vulnerability Analysis

This buffer overflow vulnerability (CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer) affects the fromaddressNat function in Tenda F456 routers. The flaw occurs when processing user-supplied input through the menufacturer/Go argument via the /goform/addressNat web interface endpoint. When malicious input exceeding expected buffer boundaries is submitted, the application fails to properly validate the input length, resulting in memory corruption beyond the allocated buffer space.

The network-accessible nature of this vulnerability makes it particularly dangerous for consumer router deployments. Attackers with low-privilege network access can reach the vulnerable endpoint and potentially achieve code execution or disrupt device operation.

Root Cause

The root cause of CVE-2026-7029 stems from improper bounds checking in the fromaddressNat function. The function processes the menufacturer/Go parameter without adequately validating the length of user-supplied input before copying it into a fixed-size memory buffer. This classic buffer overflow pattern allows attackers to overwrite adjacent memory regions, potentially corrupting program control flow or sensitive data structures.

Attack Vector

The attack vector for this vulnerability is network-based, requiring no user interaction. An authenticated attacker with low privileges can send specially crafted HTTP requests to the /goform/addressNat endpoint containing oversized data in the menufacturer/Go parameter. The vulnerable fromaddressNat function processes this malicious input, triggering the buffer overflow condition.

The exploitation typically involves:

Crafting an HTTP POST request targeting the /goform/addressNat endpoint
Including an oversized payload in the menufacturer/Go parameter
The fromaddressNat function processes the input without proper bounds validation
Memory corruption occurs, potentially allowing code execution or denial of service

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

Detection Methods for CVE-2026-7029

Indicators of Compromise

Unusual HTTP POST requests to /goform/addressNat containing abnormally large payloads
Router crashes, unexpected reboots, or instability following web interface access
Anomalous outbound network connections from the router device
Modified router configurations or unauthorized administrative accounts

Detection Strategies

Monitor HTTP traffic to Tenda F456 devices for requests to /goform/addressNat with oversized menufacturer/Go parameters
Implement network intrusion detection rules to flag anomalous POST request sizes targeting Tenda router endpoints
Deploy network segmentation to isolate IoT and router devices from untrusted network segments
Review router access logs for repeated failed authentication attempts or suspicious endpoint access patterns

Monitoring Recommendations

Enable logging on network firewalls and monitor traffic to/from Tenda router management interfaces
Implement alerting for router device crashes or unexpected reboots
Regularly audit Tenda router configurations for unauthorized changes
Consider deploying network-based anomaly detection to identify exploitation attempts

How to Mitigate CVE-2026-7029

Immediate Actions Required

Restrict network access to the router's web management interface to trusted administrators only
Disable remote administration features if not required for operations
Implement firewall rules to block external access to the /goform/addressNat endpoint
Monitor affected devices for signs of compromise or exploitation attempts

Patch Information

At the time of publication, no vendor patch has been confirmed as available for this vulnerability. Organizations should monitor Tenda's official website for firmware updates addressing CVE-2026-7029. Additional vulnerability details can be found in the VulDB entry #359609.

Workarounds

Restrict access to the router management interface to trusted internal networks only
Implement network access control lists (ACLs) to limit which hosts can reach the vulnerable endpoint
Consider replacing affected devices with alternative hardware until a patch is available
Use a VPN or other secure access method for remote administration requirements

bash

# Example iptables rules to restrict access to router management interface
# Apply on upstream firewall or network device

# Block external access to router management (adjust IP as needed)
iptables -A FORWARD -d 192.168.1.1 -p tcp --dport 80 -j DROP
iptables -A FORWARD -d 192.168.1.1 -p tcp --dport 443 -j DROP

# Allow management access only from trusted admin workstation
iptables -I FORWARD -s 192.168.1.100 -d 192.168.1.1 -p tcp --dport 80 -j ACCEPT