CVE-2025-4357 is a command injection vulnerability identified in the Tenda RX3 router firmware version 16.03.13.11_multi. The vulnerability arises from improper handling of requests to the /goform/telnet endpoint, which allows an attacker to inject arbitrary commands into the device's operating system. This flaw can be exploited remotely without requiring user interaction or authentication, as indicated by the CVSS vector (AV:N/AC:L/AT:N/UI:N/PR:H). However, the CVSS vector also notes that privileges are required (PR:H), suggesting that some level of privileged access might be necessary to exploit the vulnerability, which could limit the attack surface somewhat. The vulnerability has been publicly disclosed, but there are no known exploits in the wild at this time. The CVSS score is 5.1 (medium severity), reflecting moderate impact due to limited confidentiality, integrity, and availability impacts and the requirement for high privileges. Command injection vulnerabilities are critical because they allow attackers to execute arbitrary commands on the device, potentially leading to full device compromise, unauthorized access to network traffic, or pivoting to other devices on the network. The Tenda RX3 is a consumer-grade router commonly used in home and small office environments. The vulnerability's presence in the telnet-related endpoint is particularly concerning because telnet services are often targeted for remote exploitation due to their legacy nature and weak security controls. Given the public disclosure, attackers could develop exploits, increasing the risk over time.

For European organizations, especially small businesses and home offices relying on Tenda RX3 routers, this vulnerability poses a significant risk. Successful exploitation could lead to unauthorized command execution on the router, enabling attackers to intercept or manipulate network traffic, disrupt internet connectivity, or use the compromised device as a foothold for further attacks within the network. This could result in data breaches, service outages, and potential lateral movement to more critical infrastructure. The impact is heightened in environments where network segmentation is weak, or where these routers serve as the primary gateway to the internet. Additionally, given the medium CVSS score and the requirement for high privileges, the immediate risk to large enterprises with robust network security controls may be lower, but the risk to less protected environments remains substantial. The lack of a patch or mitigation guidance at this time increases exposure. European organizations must be vigilant, as the public disclosure may prompt attackers to develop exploits targeting this vulnerability.

1. Immediate mitigation should include disabling remote management features, especially telnet access, on affected Tenda RX3 devices to reduce the attack surface. 2. Network administrators should restrict access to the router's management interfaces to trusted internal IP addresses only, using firewall rules or access control lists. 3. Monitor network traffic for unusual activity indicative of exploitation attempts, such as unexpected outbound connections or command execution patterns. 4. Implement network segmentation to isolate vulnerable devices from critical systems, limiting potential lateral movement. 5. Regularly check for firmware updates from Tenda addressing this vulnerability and apply patches promptly once available. 6. If possible, replace affected devices with models from vendors with a stronger security track record or that have released patches. 7. Educate users and administrators about the risks of leaving default credentials or remote management enabled on consumer routers. 8. Employ intrusion detection/prevention systems (IDS/IPS) tuned to detect command injection attempts targeting router management endpoints.