Tenda F453 Stack-Based RCE via AdvSetWan (CVE-2026-3398)

Vendor-confirmed - CVE-2026-3398 is a high-severity remote code execution vulnerability in Tenda F453 router firmware 1.0.0.3 that grants unauthenticated attackers full control of the device by sending a maliciously crafted string to the WAN settings parameters. Immediate firmware update is recommended.

Overview

A critical security flaw has been identified in the Tenda F453 wireless router, firmware version 1.0.0.3. This vulnerability allows a remote attacker to send specially crafted data to the device’s web management interface, potentially leading to a complete system compromise.

Vulnerability Details

The flaw exists within the router’s web server (httpd), specifically in the function that handles Wide Area Network (WAN) settings. By sending an overly long, malicious string to the wanmode or PPPOEPassword parameter, an attacker can trigger a buffer overflow. This is a memory corruption issue where excess data overflows its allocated buffer, allowing an attacker to crash the device or, more critically, execute arbitrary code.

The attack can be performed remotely over the internet if the router’s management interface is exposed, or from within the local network. Publicly available exploit code increases the risk of active attacks.

Potential Impact

If successfully exploited, this high-severity vulnerability can have severe consequences:

• Remote Code Execution: An attacker could gain full control of the router, allowing them to intercept or redirect network traffic, steal sensitive data, and deploy malware.
• Denial of Service: The router could be crashed and rendered inoperable, causing a complete network outage for connected users.
• Persistence: An attacker could install backdoors to maintain access even after a device reboot.

Remediation and Mitigation

Immediate action is required to protect affected networks.

Primary Solution - Update Firmware:

1. Check the official Tenda support website for a firmware update that addresses CVE-2026-3398.
2. If an update is available, upgrade your Tenda F453 router to the latest patched firmware version immediately. This is the only definitive fix.

Immediate Mitigations (If No Patch is Available):

• Disable Remote Management: Ensure the router’s web management interface is not accessible from the public internet. This setting is typically found under “Administration” or “System” tools.
• Segment Your Network: Place sensitive devices on a separate network VLAN if possible, limiting the potential lateral movement of an attacker.
• Monitor Network Traffic: Be alert for unusual outbound connections or scanning activity originating from your router’s IP address.

General Best Practice: As a rule, you should regularly check for and apply firmware updates for all network hardware to protect against known vulnerabilities.