CVE-2025-45842 is a high-severity vulnerability identified in the TOTOLINK NR1800X router firmware version 9.1.0u.6681_B20230703. The flaw is an authenticated stack overflow occurring via the ssid5g parameter within the setWiFiEasyCfg function. This vulnerability is classified under CWE-121, which refers to a classic stack-based buffer overflow. The vulnerability requires an attacker to have some level of authenticated access (low privileges) to the device's management interface, as indicated by the CVSS vector (PR:L/UI:N). Exploiting this flaw allows an attacker to execute arbitrary code with high impact on confidentiality, integrity, and availability. The CVSS score of 8.8 reflects the critical nature of this vulnerability, with network attack vector (AV:N), low attack complexity (AC:L), and no user interaction (UI:N) required. Successful exploitation could lead to full compromise of the router, enabling attackers to intercept or manipulate network traffic, disrupt network services, or pivot into internal networks. Although no known exploits are reported in the wild yet, the presence of a stack overflow in a network-facing function makes it a significant risk once exploit code becomes available. The lack of an official patch link suggests that mitigation may currently rely on vendor updates or workarounds. Given the router's role in home and small office networks, this vulnerability could be leveraged for broader attacks against connected devices or as a foothold for lateral movement.

For European organizations, especially small and medium enterprises (SMEs) and home office users relying on TOTOLINK NR1800X routers, this vulnerability poses a substantial risk. Compromise of the router could lead to interception of sensitive communications, unauthorized access to internal networks, and disruption of business operations. The high impact on confidentiality, integrity, and availability means that attackers could exfiltrate data, inject malicious traffic, or cause denial of service. Given the increasing reliance on remote work and IoT devices, a compromised router can serve as a gateway for further attacks within corporate environments. Additionally, critical infrastructure or service providers using these routers could face operational disruptions. The requirement for authentication limits exposure somewhat, but default or weak credentials common in many deployments increase the likelihood of exploitation. The absence of known exploits currently provides a window for proactive mitigation, but organizations should act swiftly to prevent potential future attacks.

1. Immediately verify and update the firmware of TOTOLINK NR1800X routers to the latest version once an official patch is released by the vendor. 2. Restrict access to the router's management interface by limiting it to trusted IP addresses or internal networks only, preventing remote authenticated access. 3. Enforce strong, unique administrative credentials to reduce the risk of unauthorized authentication. 4. Monitor router logs for unusual configuration changes or access attempts to detect potential exploitation attempts early. 5. If possible, disable remote management features until the vulnerability is patched. 6. Segment critical network assets from the router's management network to minimize lateral movement in case of compromise. 7. Employ network intrusion detection systems (NIDS) to identify anomalous traffic patterns indicative of exploitation attempts. 8. Educate users and administrators about the risks of this vulnerability and the importance of timely updates and credential hygiene.