CVE-2026-4553: Tenda F453 Buffer Overflow Vulnerability

CVE-2026-4553 Overview

A stack-based buffer overflow vulnerability has been identified in the Tenda F453 router firmware version 1.0.0.3. The vulnerability exists within the fromNatlimit function located in the /goform/Natlimit endpoint, which is part of the device's Parameters Handler component. An attacker can exploit this flaw by manipulating the page argument, causing a stack-based buffer overflow that could lead to remote code execution or denial of service conditions on affected devices.

Critical Impact

This vulnerability allows remote attackers with low privileges to trigger a stack-based buffer overflow, potentially enabling arbitrary code execution on vulnerable Tenda F453 routers. A proof-of-concept exploit has been publicly disclosed.

Affected Products

• Tenda F453 firmware version 1.0.0.3

Discovery Timeline

• 2026-03-22 - CVE-2026-4553 published to NVD
• 2026-03-23 - Last updated in NVD database

Technical Details for CVE-2026-4553

Vulnerability Analysis

This vulnerability is classified under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer). The fromNatlimit function in the Tenda F453 firmware fails to properly validate the length of user-supplied input passed through the page parameter before copying it to a fixed-size stack buffer. This lack of boundary checking allows an attacker to overflow the buffer and overwrite adjacent memory, including the return address on the stack.

The attack can be initiated remotely over the network and requires only low-level privileges to execute. No user interaction is required for successful exploitation. The vulnerability impacts the confidentiality, integrity, and availability of the affected device, as successful exploitation could lead to arbitrary code execution with the privileges of the web server process running on the router.

Root Cause

The root cause of this vulnerability is improper input validation in the fromNatlimit function. The function accepts the page argument from HTTP requests to /goform/Natlimit without adequately checking its length against the size of the destination buffer. This allows an attacker to supply an oversized value that exceeds the allocated buffer space on the stack, resulting in memory corruption.

Attack Vector

The attack can be conducted remotely over the network by sending a specially crafted HTTP request to the /goform/Natlimit endpoint on the Tenda F453 router. The attacker must include a malicious page parameter value designed to overflow the stack buffer within the fromNatlimit function. By carefully crafting the overflow payload, an attacker can potentially overwrite the saved return address to redirect execution flow to attacker-controlled code.

The vulnerability is exploitable with low privileges and does not require user interaction, making it particularly dangerous in scenarios where the router's web interface is exposed to untrusted networks. Technical details and a proof-of-concept demonstrating the vulnerability are available in the GitHub PoC Repository.

Detection Methods for CVE-2026-4553

Indicators of Compromise

• Unusual HTTP requests targeting /goform/Natlimit with abnormally long page parameter values
• Router crashes, unexpected reboots, or unresponsive web interface indicating potential exploitation attempts
• Anomalous outbound network connections from the router to unknown external hosts
• Modified firmware or configuration files on the device

Detection Strategies

• Implement network intrusion detection rules to flag HTTP requests to /goform/Natlimit containing oversized page parameters
• Monitor web server logs on the Tenda F453 for requests with unusually large input values or repeated malformed requests
• Deploy deep packet inspection to identify patterns consistent with buffer overflow exploitation attempts
• Use SentinelOne Singularity to monitor for anomalous network traffic patterns and IoT device behavioral changes

Monitoring Recommendations

• Establish baseline network behavior for Tenda F453 devices and alert on deviations
• Enable verbose logging on the router if available and regularly review logs for suspicious activity
• Implement network segmentation to isolate IoT devices from critical network segments
• Utilize SentinelOne's network visibility capabilities to detect lateral movement attempts originating from compromised routers

How to Mitigate CVE-2026-4553

Immediate Actions Required

• Restrict access to the router's web management interface to trusted IP addresses only
• Disable remote management if it is not required for operations
• Place Tenda F453 routers behind a firewall that blocks external access to the web interface
• Consider replacing affected devices with alternatives from vendors that provide timely security updates
• Monitor for firmware updates from Tenda and apply them immediately when available

Patch Information

At the time of publication, no official patch has been released by Tenda for this vulnerability. Organizations should monitor the Tenda Website for security advisories and firmware updates. Additional vulnerability tracking information is available through VulDB #352380.

Workarounds

• Disable external access to the web management interface by configuring the router to only accept connections from the local network
• Implement firewall rules to block inbound traffic to port 80/443 on the router's WAN interface
• Use access control lists to restrict management interface access to specific administrator IP addresses
• Consider deploying a network firewall or intrusion prevention system in front of the router to filter malicious requests
• Regularly monitor the device for signs of compromise until an official patch is available

# Example firewall rule to restrict access to router management interface
# Apply on upstream firewall or gateway device

# Block external access to router web interface (replace ROUTER_IP with actual IP)
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 only trusted management IP (replace ADMIN_IP with trusted address)
iptables -I FORWARD -s ADMIN_IP -d ROUTER_IP -p tcp --dport 80 -j ACCEPT