CVE-2026-4567 identifies a critical security vulnerability in the Tenda A15 router firmware version 15.13.07.13. The vulnerability is a stack-based buffer overflow located in the UploadCfg function within the /cgi-bin/UploadCfg CGI endpoint. Specifically, the vulnerability arises from improper validation and handling of the File argument passed to this function, allowing an attacker to overwrite the stack memory. This flaw can be triggered remotely without requiring any authentication or user interaction, making it highly exploitable over the network. Exploiting this vulnerability could allow an attacker to execute arbitrary code on the device, leading to full compromise of the router. The CVSS 4.0 score of 9.3 reflects the critical nature of this vulnerability, with network attack vector, low attack complexity, no privileges or user interaction required, and high impact on confidentiality, integrity, and availability. Although no known exploits are currently active in the wild, the public disclosure of the exploit details increases the likelihood of exploitation attempts. The vulnerability affects a widely deployed consumer and small business router model, which is often used as a gateway device, making it a valuable target for attackers aiming to intercept or manipulate network traffic, launch further attacks, or disrupt network availability. No official patches have been linked yet, emphasizing the need for immediate attention and mitigation by users and administrators.

The impact of CVE-2026-4567 is severe for organizations and individuals using the Tenda A15 router with the affected firmware. Successful exploitation can lead to arbitrary code execution on the router, enabling attackers to take full control of the device. This can result in interception and manipulation of network traffic, unauthorized access to internal networks, deployment of malware or botnets, and potential disruption of internet connectivity. The compromise of a network gateway device like the Tenda A15 can undermine the security of all connected devices, leading to widespread data breaches and operational outages. Given the router’s role in home and small business environments, the vulnerability could facilitate espionage, data theft, or ransomware attacks. The lack of required authentication and user interaction significantly increases the risk, as attackers can remotely exploit the vulnerability without alerting users. The public disclosure of exploit details further elevates the threat level, potentially leading to rapid exploitation campaigns targeting vulnerable devices worldwide.

To mitigate CVE-2026-4567, organizations and users should take the following specific actions: 1) Immediately check for and apply any official firmware updates or patches released by Tenda addressing this vulnerability. 2) If no patch is available, consider temporarily disabling remote management features or restricting access to the /cgi-bin/UploadCfg endpoint via firewall rules or access control lists to prevent remote exploitation. 3) Segment the network to isolate vulnerable devices from critical infrastructure and sensitive data. 4) Monitor network traffic for unusual activity or attempts to access the vulnerable endpoint, using intrusion detection systems or network monitoring tools. 5) Replace affected devices with models from vendors with a strong security track record if patching is not feasible. 6) Educate users about the risks of using outdated router firmware and the importance of timely updates. 7) Implement network-level protections such as VPNs and strong authentication for remote access to reduce exposure. These targeted measures go beyond generic advice by focusing on immediate containment and long-term remediation specific to the vulnerability’s attack vector and affected device.