CVE-2026-7032: Tenda F456 Buffer Overflow Vulnerability

CVE-2026-7032 Overview

A buffer overflow vulnerability has been identified in Tenda F456 firmware version 1.0.0.5. The vulnerability exists in the SafeEmailFilter function located in the /goform/SafeEmailFilter endpoint. Improper handling of the page argument allows attackers to trigger a buffer overflow condition. This vulnerability can be exploited remotely, and proof-of-concept information has been publicly disclosed.

Critical Impact
Remote attackers can exploit this buffer overflow to potentially achieve code execution, crash the device, or gain unauthorized control over the affected Tenda F456 router.

Affected Products

Tenda F456 Firmware version 1.0.0.5
Tenda F456 Hardware

Discovery Timeline

2026-04-26 - CVE-2026-7032 published to NVD
2026-04-29 - Last updated in NVD database

Technical Details for CVE-2026-7032

Vulnerability Analysis

This vulnerability is classified as CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer). The SafeEmailFilter function fails to properly validate the length of user-supplied input for the page parameter before copying it into a fixed-size buffer. When an attacker supplies an oversized value, the function writes beyond the allocated memory boundaries, corrupting adjacent memory regions.

The network-based attack vector allows exploitation without physical access to the device. An authenticated attacker with low privileges can remotely trigger this condition by sending crafted HTTP requests to the vulnerable endpoint on the router's web management interface.

Root Cause

The root cause lies in insufficient bounds checking within the SafeEmailFilter function. The code fails to validate that user-controlled input fits within the destination buffer before performing memory operations. This classic buffer overflow pattern occurs when the application blindly trusts input length without implementing proper size constraints or utilizing safer memory handling functions.

Attack Vector

The vulnerability is exploited via network-based HTTP requests to the /goform/SafeEmailFilter endpoint. An attacker sends a specially crafted request containing an oversized page parameter value. When the vulnerable function processes this input, the buffer overflow occurs, potentially allowing:

Denial of service through device crash
Code execution by overwriting return addresses or function pointers
Memory corruption leading to unpredictable device behavior

The exploitation mechanism involves sending malformed HTTP POST requests to the router's web interface with a manipulated page argument that exceeds expected buffer sizes. Technical details and proof-of-concept information are available in the GitHub vulnerability repository.

Detection Methods for CVE-2026-7032

Indicators of Compromise

Unexpected crashes or reboots of Tenda F456 routers
Anomalous HTTP POST requests targeting /goform/SafeEmailFilter with unusually large page parameter values
Unusual outbound network traffic from the router indicating potential compromise
Evidence of unauthorized configuration changes on the device

Detection Strategies

Monitor HTTP traffic to Tenda F456 management interfaces for oversized parameter values in requests to /goform/SafeEmailFilter
Implement network intrusion detection rules to flag requests with abnormally long page parameters
Deploy web application firewall (WAF) rules to block malformed requests to vulnerable endpoints
Enable logging on network segments containing Tenda routers to capture suspicious activity

Monitoring Recommendations

Configure network monitoring tools to alert on repeated crashes or restarts of Tenda F456 devices
Implement traffic analysis for HTTP POST requests to router management interfaces
Establish baseline network behavior for routers and alert on deviations
Review router access logs regularly for signs of exploitation attempts

How to Mitigate CVE-2026-7032

Immediate Actions Required

Restrict access to the Tenda F456 web management interface to trusted IP addresses only
Disable remote management access if not required for operations
Place affected routers behind network segmentation to limit attack surface
Monitor for vendor firmware updates and apply patches when available

Patch Information

As of the last update on 2026-04-29, no vendor patch information is available in the NVD data. Organizations should monitor the Tenda Official Website for security advisories and firmware updates. Additional vulnerability details are tracked in VulDB #359612.

Workarounds

Implement access control lists (ACLs) to restrict management interface access to specific trusted networks or IP addresses
Disable the web management interface entirely if device configuration can be managed through alternative methods
Deploy a firewall in front of the affected device to filter and inspect incoming HTTP requests
Consider replacing vulnerable devices with alternative hardware if vendor patches are not released in a timely manner

bash

# Example: Restrict management interface access via upstream firewall
# Block external access to router management port (typically 80/443)
iptables -A FORWARD -d <router_ip> -p tcp --dport 80 -j DROP
iptables -A FORWARD -d <router_ip> -p tcp --dport 443 -j DROP

# Allow management access only from trusted admin network
iptables -I FORWARD -s <trusted_admin_subnet> -d <router_ip> -p tcp --dport 80 -j ACCEPT