CVE-2026-3726 is a stack-based buffer overflow vulnerability identified in the Tenda F453 router firmware version 1.0.0.3. The vulnerability exists in the fromwebExcptypemanFilter function, specifically in the handling of the 'page' argument passed to the /goform/webExcptypemanFilter endpoint. Improper validation or bounds checking of this argument allows an attacker to overflow the stack buffer, potentially overwriting the return address or other control data on the stack. This can lead to arbitrary code execution with the privileges of the affected process. The vulnerability is remotely exploitable over the network without requiring authentication or user interaction, making it highly dangerous. The CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P) indicates network attack vector, low attack complexity, no authentication or user interaction required, and high impact on confidentiality, integrity, and availability. Although no exploits have been observed in the wild yet, public disclosure of exploit code increases the risk of imminent attacks. The affected device, Tenda F453, is a consumer and small business router, often deployed in home and small office environments, which may lack robust security monitoring. The absence of available patches or updates at the time of disclosure further exacerbates the risk. This vulnerability could allow attackers to gain control over the router, intercept or manipulate network traffic, disrupt network availability, or pivot to internal networks.

The impact of CVE-2026-3726 is significant for organizations relying on Tenda F453 routers. Successful exploitation can lead to full compromise of the device, allowing attackers to execute arbitrary code with elevated privileges. This can result in interception or manipulation of sensitive network traffic, disruption of network services, and potential lateral movement within internal networks. For small businesses and home users, this could mean loss of confidentiality and integrity of communications, exposure to further malware infections, or use of the device as a foothold for broader attacks. Enterprises using these devices in branch offices or remote locations may face operational disruptions and increased risk of data breaches. The lack of authentication and user interaction requirements lowers the barrier for attackers, increasing the likelihood of exploitation. The public availability of exploit code further raises the threat level, potentially leading to widespread attacks. Overall, the vulnerability threatens confidentiality, integrity, and availability of network infrastructure, which are critical for organizational security and business continuity.

1. Immediate mitigation should include isolating affected Tenda F453 devices from untrusted networks to reduce exposure to remote attacks. 2. Network administrators should implement strict firewall rules to restrict access to the router's management interfaces, especially the /goform/webExcptypemanFilter endpoint, limiting it to trusted IP addresses only. 3. Monitor network traffic for unusual activity or signs of exploitation attempts targeting the vulnerable endpoint. 4. Employ network segmentation to limit the impact of a compromised router on critical internal systems. 5. Regularly check for firmware updates or security advisories from Tenda and apply patches promptly once available. 6. Consider replacing affected devices with models from vendors with a stronger security track record if patches are not forthcoming. 7. Use intrusion detection/prevention systems (IDS/IPS) with signatures for this vulnerability once they become available. 8. Educate users and administrators about the risks of exposing router management interfaces to the internet. 9. Conduct periodic security assessments of network devices to identify and remediate similar vulnerabilities proactively.