CVE-2026-3399 is a buffer overflow vulnerability identified in the Tenda F453 router firmware version 1.0.0.3. The vulnerability resides in the httpd component, specifically within the fromGstDhcpSetSer function that processes the dips argument in the /goform/GstDhcpSetSer endpoint. Improper handling of this argument allows an attacker to overflow a buffer, which can lead to arbitrary code execution or denial of service on the device. The vulnerability is remotely exploitable without requiring authentication or user interaction, making it highly accessible to attackers. The CVSS 4.0 base score of 8.7 reflects the high impact on confidentiality, integrity, and availability, combined with low attack complexity and no privileges or user interaction needed. While no confirmed exploits in the wild have been reported, a public exploit exists, increasing the likelihood of future attacks. The vulnerability affects a widely used consumer and small business router, which often serves as a gateway device, making exploitation potentially impactful for network security. The lack of available patches at the time of disclosure necessitates immediate mitigation efforts to reduce exposure.

The impact of CVE-2026-3399 is significant for organizations and individuals using the Tenda F453 router. Successful exploitation can lead to full compromise of the device, allowing attackers to execute arbitrary code, disrupt network availability, or intercept and manipulate network traffic. This can result in loss of confidentiality of sensitive data, integrity violations through unauthorized configuration changes or malware installation, and availability issues due to device crashes or reboots. Given that routers are critical network infrastructure components, compromise can serve as a foothold for lateral movement within internal networks or as a launchpad for further attacks. The remote and unauthenticated nature of the exploit increases the risk of widespread attacks, especially in environments where these devices are exposed to untrusted networks or the internet. Organizations relying on Tenda F453 routers without mitigations risk significant operational disruption and data breaches.

1. Immediately isolate Tenda F453 devices from untrusted networks, especially the internet, to prevent remote exploitation. 2. Disable remote management interfaces and services on the router to reduce attack surface. 3. Implement network segmentation to limit the impact of a compromised device on critical internal systems. 4. Monitor network traffic for unusual requests targeting /goform/GstDhcpSetSer or other suspicious activity indicative of exploitation attempts. 5. Apply any vendor-provided firmware updates or patches as soon as they become available. 6. If patches are unavailable, consider replacing affected devices with models not vulnerable to this issue. 7. Employ intrusion detection/prevention systems (IDS/IPS) with signatures for this vulnerability or exploit attempts. 8. Educate network administrators about the vulnerability and the importance of timely mitigation. 9. Regularly audit router configurations and logs for signs of compromise or unauthorized changes. 10. Restrict physical and administrative access to the devices to prevent local exploitation or configuration tampering.