CVE-2026-3810 identifies a stack-based buffer overflow vulnerability in the Tenda FH1202 router firmware version 1.2.0.14(408). The vulnerability resides in the fromDhcpListClient function, specifically in the handling of the 'page' argument passed to the /goform/DhcpListClient endpoint. Improper input validation or bounds checking allows an attacker to overflow the stack buffer, which can lead to overwriting control data such as return addresses. This flaw is exploitable remotely over the network without requiring authentication or user interaction, making it highly dangerous. Successful exploitation could allow an attacker to execute arbitrary code with elevated privileges on the device, potentially leading to full device compromise. The vulnerability was publicly disclosed on March 9, 2026, with exploit code available, although no active exploitation has been reported yet. The CVSS 4.0 base score of 8.7 reflects the vulnerability's high impact on confidentiality, integrity, and availability, with low attack complexity and no privileges or user interaction required. The affected product, Tenda FH1202, is a consumer-grade router commonly deployed in residential and small business environments, particularly in Asia and emerging markets. The lack of an official patch or update link in the disclosure suggests that mitigation may require vendor intervention or temporary workarounds. Due to the critical nature of the flaw and the potential for remote code execution, organizations should treat this vulnerability with high priority.

The impact of CVE-2026-3810 is significant for organizations and individuals using the Tenda FH1202 router version 1.2.0.14(408). Exploitation can lead to arbitrary code execution on the device, allowing attackers to gain full control over the router. This can result in interception or manipulation of network traffic, disruption of network availability, and the establishment of persistent backdoors for further attacks. Compromised routers can be leveraged as entry points into internal networks, facilitating lateral movement and data exfiltration. The vulnerability's remote exploitability without authentication increases the attack surface, making large-scale automated attacks feasible once exploit code is widely adopted. This poses a particular risk to small businesses and home users who may lack robust network defenses or timely patch management. Additionally, compromised routers can be conscripted into botnets for distributed denial-of-service (DDoS) attacks, amplifying the threat to broader internet infrastructure. The absence of a patch at the time of disclosure further exacerbates the risk, necessitating immediate mitigation efforts to reduce exposure.

To mitigate CVE-2026-3810 effectively, organizations should first check for any firmware updates or patches released by Tenda addressing this vulnerability and apply them promptly. In the absence of an official patch, network administrators should disable remote management interfaces on the affected routers to prevent external exploitation. Implement network segmentation to isolate vulnerable devices from critical infrastructure and sensitive data. Employ firewall rules to restrict access to the /goform/DhcpListClient endpoint and monitor network traffic for unusual requests targeting this URI. Use intrusion detection and prevention systems (IDS/IPS) with signatures tuned to detect exploitation attempts of this specific buffer overflow. Regularly audit router configurations and logs for signs of compromise or anomalous behavior. Consider replacing affected devices with models from vendors with a stronger security track record if patching is not feasible. Educate users about the risks of using outdated firmware and the importance of timely updates. Finally, maintain backups of router configurations to facilitate rapid recovery in case of compromise.