CVE-2025-4849 is a command injection vulnerability identified in the TOTOLINK N300RH router, specifically in firmware version 6.1c.1390_B20191101. The vulnerability resides in the CloudACMunualUpdateUserdata function within the /cgi-bin/cstecgi.cgi file. An attacker can manipulate the 'url' argument passed to this function to inject arbitrary commands that the device executes. This vulnerability is remotely exploitable without requiring user interaction or authentication, making it particularly dangerous. The CVSS 4.0 base score is 5.3 (medium severity), reflecting the fact that while the attack vector is network-based and requires no user interaction, it does require low privileges (PR:L) and has limited impact on confidentiality, integrity, and availability. The vulnerability does not affect system confidentiality, integrity, or availability to a high degree, but successful exploitation could allow an attacker to execute arbitrary commands on the device, potentially leading to device compromise, network pivoting, or disruption of network services. Although no public exploits are currently known in the wild, the disclosure of the vulnerability and the availability of technical details increase the risk of exploitation. The TOTOLINK N300RH is a consumer-grade wireless router, commonly used in home and small office environments, which may be deployed in European households and small businesses. The lack of an official patch or mitigation guidance at this time increases the urgency for affected users to take protective measures.

For European organizations, especially small businesses and home users relying on TOTOLINK N300RH routers, this vulnerability poses a risk of unauthorized remote command execution. Exploitation could lead to device takeover, enabling attackers to intercept or manipulate network traffic, launch further attacks within the local network, or disrupt internet connectivity. This could compromise sensitive data confidentiality and network integrity. In environments where these routers are used as gateways to critical systems or sensitive information, the impact could extend to broader organizational security. Given the medium severity score, the threat is significant but not catastrophic; however, the ease of remote exploitation without user interaction or authentication elevates the risk profile. The absence of known exploits in the wild currently limits immediate widespread impact, but the public disclosure may lead to rapid development of exploit tools. European organizations with limited IT security resources may be particularly vulnerable due to potential delays in firmware updates or device replacement.

1. Immediate mitigation should include isolating the affected TOTOLINK N300RH devices from critical network segments to limit potential lateral movement if compromised. 2. Network administrators should monitor network traffic for unusual outbound connections or command-and-control indicators originating from these routers. 3. Users should check for firmware updates from TOTOLINK regularly; if no patch is available, consider replacing the device with a more secure router model. 4. Disable remote management features on the router to reduce exposure to external attackers. 5. Implement network segmentation to restrict access to the router's management interface only to trusted internal hosts. 6. Employ intrusion detection/prevention systems (IDS/IPS) to detect exploitation attempts targeting the /cgi-bin/cstecgi.cgi endpoint. 7. Educate users on the risks of using outdated or unsupported network devices and encourage timely updates or replacements. 8. For organizations, consider deploying network access controls and endpoint security solutions to detect and respond to potential compromises stemming from this vulnerability.