CVE-2026-3398 is a buffer overflow vulnerability identified in the Tenda F453 router firmware version 1.0.0.3. The flaw exists in the fromAdvSetWan function within the /goform/AdvSetWan HTTP endpoint, which processes WAN configuration parameters. Specifically, the vulnerability is triggered by manipulating the wanmode or PPPOEPassword parameters, which are not properly validated or bounded, leading to a buffer overflow condition. This vulnerability can be exploited remotely over the network without requiring authentication or user interaction, making it highly accessible to attackers. The buffer overflow can corrupt memory, potentially allowing attackers to execute arbitrary code with elevated privileges or cause a denial of service by crashing the device. The vulnerability has been publicly disclosed, though no known exploits have been observed in the wild yet. The CVSS 4.0 score of 8.7 reflects the high impact on confidentiality, integrity, and availability, combined with the ease of remote exploitation. The affected product, Tenda F453, is a consumer-grade router commonly used in residential and small business environments, which may lack robust security monitoring. The absence of available patches at the time of disclosure increases the urgency for mitigation. Attackers exploiting this flaw could gain control over the router, intercept or manipulate network traffic, and pivot to internal networks, posing significant security risks.

The impact of CVE-2026-3398 is substantial for organizations and individuals using the Tenda F453 router. Exploitation can lead to remote code execution, allowing attackers to take full control of the affected device. This compromises the confidentiality and integrity of network traffic passing through the router, enabling interception, modification, or redirection of sensitive data. Additionally, attackers could disrupt network availability by causing device crashes or reboots. For organizations, this could result in network outages, data breaches, and lateral movement into internal systems. Small businesses and home users are particularly vulnerable due to limited security resources and potential lack of timely firmware updates. The public disclosure of the vulnerability increases the likelihood of exploitation attempts, especially by opportunistic attackers and automated scanning tools. Without mitigation, the vulnerability could be leveraged in botnets or as a foothold for further attacks, amplifying its impact across affected networks.

To mitigate CVE-2026-3398, organizations should immediately identify all Tenda F453 devices running firmware version 1.0.0.3. Since no official patches are currently available, temporary mitigations include restricting remote access to the router's management interface by disabling WAN-side HTTP access or applying firewall rules to block incoming traffic to the /goform/AdvSetWan endpoint. Network segmentation should be enforced to isolate vulnerable devices from critical infrastructure. Monitoring network traffic for unusual requests targeting the vulnerable endpoint can help detect exploitation attempts. Users should regularly check for firmware updates from Tenda and apply them promptly once released. Additionally, replacing affected devices with models from vendors with stronger security track records may be considered for long-term risk reduction. Employing intrusion detection systems capable of recognizing buffer overflow attack patterns targeting HTTP services can provide early warning. Finally, educating users about the risks of exposing router management interfaces to the internet is essential to prevent exploitation.