CVE-2026-2930 is a stack-based buffer overflow vulnerability found in the Tenda A18 router firmware version 15.13.07.13. The flaw exists in the webCgiGetUploadFile function within the /cgi-bin/UploadCfg component of the HTTP daemon service. This function improperly handles the boundary of an input argument, allowing an attacker to overflow the stack buffer by sending specially crafted requests. The overflow can corrupt the stack, potentially enabling remote code execution or denial of service. The vulnerability is remotely exploitable without requiring authentication or user interaction, increasing its risk profile. While the CVSS 4.0 score is 5.3 (medium), the presence of a public exploit increases the urgency for remediation. The vulnerability affects only the specified firmware version and does not appear to require complex conditions for exploitation. No patches have been linked yet, so mitigation relies on network controls and firmware updates once available.

If exploited, this vulnerability could allow attackers to execute arbitrary code on affected Tenda A18 routers, potentially leading to full device compromise. This could result in unauthorized access to the internal network, interception or manipulation of network traffic, and disruption of network services. The compromise of routers can serve as a foothold for further attacks against connected devices or as part of botnets for large-scale attacks. Given the medium CVSS score, the impact on confidentiality, integrity, and availability is moderate but significant in environments relying on these routers for secure network access. The lack of authentication requirement and remote exploitability increase the risk of widespread attacks, especially in unmanaged or poorly secured networks.

Organizations should immediately identify any Tenda A18 routers running firmware version 15.13.07.13 and prioritize their upgrade once a vendor patch is released. Until a patch is available, network administrators should restrict access to the router’s management interface by limiting it to trusted IP addresses and disabling remote management where possible. Implementing network segmentation can reduce the impact of a compromised device. Monitoring network traffic for unusual activity related to the /cgi-bin/UploadCfg endpoint can help detect exploitation attempts. Additionally, deploying intrusion detection/prevention systems (IDS/IPS) with signatures for this vulnerability can provide proactive defense. Regularly reviewing and updating router firmware and configurations is essential to maintain security posture.