CVE-2026-3377:

Overview

A critical security vulnerability has been identified in the Tenda F453 wireless router, firmware version 1.0.0.3. This flaw allows a remote attacker to send specially crafted data to the device, triggering a buffer overflow condition. The vulnerability is located in the web management interface’s fromSafeUrlFilter function, which is responsible for processing URL filter settings.

Vulnerability Details

In simple terms, the router’s software contains a specific function designed to handle website filtering rules. This function does not properly check the size of the input data it receives. By sending an overly long, manipulated string to the affected component (/goform/SafeUrlFilter), an attacker can overflow a memory buffer. This overflow can corrupt the router’s normal operation and potentially allow the attacker to run their own malicious code on the device.

Impact

The impact of this vulnerability is severe. A successful exploit could allow an unauthenticated, remote attacker to:

• Take full control of the router, changing all settings including DNS and administrative credentials.
• Intercept or redirect network traffic, enabling data theft or further attacks on devices within the local network.
• Render the router inoperable (brick it), causing a denial of service for all connected users.
• Use the compromised router as a foothold to launch attacks against other internal devices, such as computers, phones, or smart home appliances.

The vulnerability is rated as HIGH severity with a CVSS score of 8.8. Public exploit code increases the immediate risk of active attacks.

Remediation and Mitigation

As of now, Tenda has not released an official firmware update addressing CVE-2026-3377. Users and administrators must take the following steps immediately:

1. Apply Firmware Updates: Continuously monitor the official Tenda support website for the F453 model. Apply any new firmware version as soon as it becomes available. Do not use version 1.0.0.3.
2. Implement Network Segmentation: If the router cannot be replaced or updated, isolate it on your network. Do not place it in a position where it protects critical internal segments or sensitive devices.
3. Restrict Management Access: Ensure the router’s web management interface is not accessible from the public internet (WAN). This setting is often labeled “Remote Management” and should be disabled.
4. Consider Replacement: If no security patch is provided by the vendor in a reasonable timeframe, consider replacing the affected hardware with a supported model from a vendor that actively maintains its products.

Immediate Action: Administrators should verify if they are using the Tenda F453 router and check its firmware version. Any device running version 1.0.0.3 should be considered vulnerable and mitigation steps should be applied without delay.