CVE-2026-4974 identifies a critical stack-based buffer overflow vulnerability in the Tenda AC7 router firmware version 15.03.06.44. The vulnerability resides in the fromSetSysTime function, which processes the Time parameter received via a POST request to the /goform/SetSysTimeCfg endpoint. Improper validation or bounds checking of this input 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 elevated privileges on the device. The flaw can be triggered remotely over the network without requiring authentication or user interaction, increasing the attack surface significantly. The CVSS v4.0 score of 8.7 reflects the high impact on confidentiality, integrity, and availability, combined with low attack complexity and no required privileges. Although no active exploitation has been reported, the public availability of an exploit increases the likelihood of future attacks. 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 seeking to compromise home or enterprise networks. The absence of an official patch at the time of disclosure necessitates immediate mitigation efforts to reduce exposure.

Successful exploitation of this vulnerability allows remote attackers to execute arbitrary code on the Tenda AC7 router with elevated privileges, potentially leading to full device compromise. This can result in unauthorized access to network traffic, interception or manipulation of data, disruption of network services, and use of the compromised device as a foothold for lateral movement or launching further attacks. Given the router’s role as a network gateway, the impact extends beyond the device itself to all connected systems, increasing the risk of widespread network compromise. The vulnerability threatens confidentiality by exposing sensitive network data, integrity by enabling unauthorized configuration changes or malware installation, and availability by causing device crashes or denial of service. The ease of exploitation and remote attack vector make this a critical threat for organizations and individuals relying on Tenda AC7 routers, particularly in environments lacking robust network segmentation or monitoring.

1. Immediately restrict access to the router’s management interfaces by limiting exposure to trusted internal networks only, using firewall rules or VLAN segmentation. 2. Monitor network traffic for suspicious POST requests targeting /goform/SetSysTimeCfg, especially those containing anomalous Time parameter values. 3. Disable remote management features if not required to reduce the attack surface. 4. Implement network-level intrusion detection or prevention systems (IDS/IPS) with signatures or heuristics to detect exploitation attempts of this vulnerability. 5. Regularly check for firmware updates from Tenda and apply patches as soon as they become available. 6. If patching is not immediately possible, consider replacing affected devices with alternative hardware from vendors with timely security support. 7. Educate network administrators about this vulnerability and the importance of securing router management interfaces. 8. Employ network segmentation to isolate critical systems from potentially compromised routers. 9. Use strong authentication and encrypted management protocols where supported to reduce risk of unauthorized access.