CVE-2026-3169: Tenda F453 Buffer Overflow Vulnerability

CVE-2026-3169 Overview

A buffer overflow vulnerability has been identified in the Tenda F453 router firmware version 1.0.0.3. This security flaw affects the fromSafeEmailFilter function within the /goform/SafeEmailFilter endpoint of the httpd web service component. 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

This network-accessible vulnerability enables remote attackers with low-level privileges to potentially execute arbitrary code or crash the affected device by exploiting the buffer overflow condition in the web management interface.

Affected Products

• Tenda F453 Firmware version 1.0.0.3
• Tenda F453 Hardware

Discovery Timeline

• 2026-02-25 - CVE-2026-3169 published to NVD
• 2026-02-25 - Last updated in NVD database

Technical Details for CVE-2026-3169

Vulnerability Analysis

The vulnerability resides in the fromSafeEmailFilter function which handles HTTP requests to the /goform/SafeEmailFilter endpoint on the Tenda F453 router's web management interface. The function fails to properly validate the length of user-supplied input for the page argument before copying it into a fixed-size buffer.

This implementation flaw allows attackers to craft malicious HTTP requests containing oversized page parameter values that exceed the allocated buffer space. When the function processes such input, it writes data beyond the buffer boundaries, corrupting adjacent memory regions.

The vulnerability is classified under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer), indicating that the affected code fails to ensure memory operations stay within intended boundaries.

Root Cause

The root cause stems from insufficient bounds checking in the fromSafeEmailFilter function. The code processes the page parameter from incoming HTTP requests without verifying that the input length does not exceed the destination buffer capacity. This classic buffer overflow pattern allows memory corruption when processing crafted requests.

Attack Vector

The attack vector is network-based, requiring the attacker to send specially crafted HTTP requests to the vulnerable /goform/SafeEmailFilter endpoint. The attack characteristics include:

• Network Accessibility: The vulnerability can be exploited remotely over the network without requiring physical access to the device
• Low Privilege Requirement: Attackers need only low-level authentication to access the vulnerable endpoint
• No User Interaction: Exploitation does not require any action from legitimate users
• Direct Impact: Successful exploitation affects confidentiality, integrity, and availability of the device

The exploit has been publicly disclosed according to the vulnerability report, and technical details are available through the GitHub Vulnerability Database Entry.

Detection Methods for CVE-2026-3169

Indicators of Compromise

• Unusual HTTP requests to /goform/SafeEmailFilter with abnormally large page parameter values
• Unexpected router reboots or crashes coinciding with web interface access attempts
• Suspicious network traffic patterns targeting the router's management interface on standard HTTP ports
• Anomalous memory consumption or process behavior on the httpd service

Detection Strategies

• Deploy network intrusion detection rules to identify HTTP requests to /goform/SafeEmailFilter with oversized parameters
• Monitor router system logs for httpd service crashes or unexpected restarts
• Implement web application firewall rules to block requests exceeding expected parameter lengths for router management endpoints
• Analyze network traffic for patterns consistent with buffer overflow exploitation attempts

Monitoring Recommendations

• Configure alerting for repeated failed or malformed requests to router management endpoints
• Establish baseline behavior for router management interface traffic and alert on deviations
• Monitor for unauthorized access attempts to the router's web administration interface
• Review network logs for reconnaissance activity targeting Tenda devices

How to Mitigate CVE-2026-3169

Immediate Actions Required

• Restrict access to the router's web management interface to trusted internal networks only
• Implement firewall rules to block external access to the /goform/SafeEmailFilter endpoint
• Disable remote management features if not required for operational purposes
• Monitor vendor channels for firmware updates addressing this vulnerability

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 and firmware releases. Additional technical information is available through VulDB #347676.

Workarounds

• Implement network segmentation to isolate the router's management interface from untrusted networks
• Use a VPN or jump host to access router management functions, limiting direct exposure
• Configure access control lists (ACLs) to restrict management interface access to specific administrator IP addresses
• Consider deploying a web application firewall or reverse proxy with input validation to filter malicious requests

# Example: Restrict management access via firewall (iptables)
# Block external access to router management interface
iptables -A INPUT -p tcp --dport 80 -s ! 192.168.1.0/24 -j DROP
iptables -A INPUT -p tcp --dport 443 -s ! 192.168.1.0/24 -j DROP

# Allow management access only from specific admin workstation
iptables -A INPUT -p tcp --dport 80 -s 192.168.1.100 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -s 192.168.1.100 -j ACCEPT