CVE-2026-4554 is a command injection vulnerability affecting Tenda F453 routers running firmware version 1.0.0.3. The vulnerability resides in the FormWriteFacMac function, specifically in the /goform/WriteFacMac endpoint, where the 'mac' parameter is improperly sanitized. This flaw enables remote attackers to inject and execute arbitrary system commands on the affected device without requiring authentication or user interaction. The attack vector is network-based, allowing exploitation over the internet or local networks where the device is accessible. The vulnerability arises due to insufficient input validation, permitting malicious payloads to be passed directly to system-level command execution functions. Although the CVSS 4.0 score is 5.3, indicating medium severity, the impact includes potential unauthorized access to device configuration, disruption of network services, and possible pivoting to internal networks. No official patches or firmware updates have been released at the time of disclosure, but public exploit code is available, increasing the risk of exploitation. The vulnerability does not require privileges or user interaction, making it easier to exploit in exposed environments. This flaw highlights the importance of secure coding practices, especially for network device management interfaces.

The exploitation of CVE-2026-4554 can have significant consequences for organizations relying on Tenda F453 routers. Attackers can execute arbitrary commands remotely, potentially leading to unauthorized configuration changes, data leakage, or denial of service. This can compromise the confidentiality, integrity, and availability of the affected network device and connected infrastructure. In enterprise or critical environments, compromised routers can serve as entry points for lateral movement, enabling attackers to access sensitive internal systems. The lack of authentication requirement and remote exploitability increases the attack surface, especially for devices exposed to the internet or untrusted networks. Although the CVSS score is medium, the real-world impact depends on the deployment context; routers in sensitive or high-value environments face elevated risks. The absence of patches means organizations must rely on network-level mitigations until firmware updates are available. Public availability of exploit code further raises the likelihood of active exploitation attempts, potentially leading to widespread attacks if not addressed promptly.

1. Immediately restrict access to the management interface of Tenda F453 routers by limiting exposure to trusted networks only, using firewall rules or network segmentation. 2. Disable remote management features if not required, especially WAN-side access to the /goform/WriteFacMac endpoint. 3. Monitor network traffic for unusual requests targeting /goform/WriteFacMac or suspicious command injection patterns. 4. Employ intrusion detection/prevention systems (IDS/IPS) with signatures or heuristics capable of detecting command injection attempts against Tenda devices. 5. Regularly audit router configurations and logs for signs of unauthorized changes or exploitation attempts. 6. Contact Tenda support or monitor official channels for firmware updates addressing this vulnerability and apply patches promptly once available. 7. As an interim measure, consider deploying web application firewalls (WAF) or reverse proxies that can sanitize or block malicious input targeting vulnerable endpoints. 8. Educate network administrators about the risks of exposing management interfaces and enforce strict access controls and strong authentication mechanisms where possible.