CVE-2025-45844 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 in the setWiFiBasicCfg function, specifically via the ssid parameter. This vulnerability is classified under CWE-121, which corresponds to a classic stack-based buffer overflow. Exploiting this vulnerability requires an attacker to have authenticated access to the device, meaning they must already possess valid credentials or otherwise bypass authentication mechanisms. Once exploited, the stack overflow can lead to arbitrary code execution with the privileges of the affected process, potentially allowing an attacker to fully compromise the router. The CVSS v3.1 base score is 8.8, indicating a high impact on confidentiality, integrity, and availability. The vector metrics specify that the attack can be performed remotely over the network (AV:N), with low attack complexity (AC:L), requiring privileges (PR:L), no user interaction (UI:N), and the scope remains unchanged (S:U). The impact on confidentiality, integrity, and availability is rated high (C:H/I:H/A:H), meaning the attacker can gain sensitive information, modify configurations or firmware, and disrupt network availability. No public exploits are currently known in the wild, and no patches or vendor advisories are listed yet. The vulnerability affects a specific firmware version of the TOTOLINK NR1800X, a consumer and small office/home office (SOHO) router model. The stack overflow via the ssid parameter suggests that the input validation or bounds checking for the SSID configuration is insufficient, allowing crafted input to overwrite the stack memory. This can lead to control flow hijacking and execution of malicious payloads. Given the router's role as a network gateway, successful exploitation could enable attackers to intercept, manipulate, or disrupt network traffic, pivot to internal networks, or establish persistent footholds.

For European organizations, especially small and medium enterprises (SMEs) and home office users relying on TOTOLINK NR1800X routers, this vulnerability poses a significant risk. Compromise of these routers can lead to interception of sensitive communications, unauthorized network access, and potential lateral movement within corporate networks. The high impact on confidentiality, integrity, and availability means that attackers could exfiltrate sensitive data, alter network configurations, or cause denial of service conditions. Given that the vulnerability requires authentication, insider threats or compromised credentials could facilitate exploitation. Additionally, the lack of patches increases the window of exposure. In sectors such as finance, healthcare, and critical infrastructure where network integrity is paramount, exploitation could disrupt operations and lead to regulatory compliance issues under GDPR and other data protection laws. The risk is amplified in remote work scenarios where home routers serve as the primary network gateway.

1. Immediate mitigation should focus on restricting access to the router's management interface to trusted networks and users only, employing strong, unique credentials to prevent unauthorized authentication. 2. Network segmentation should be implemented to isolate vulnerable routers from critical internal systems, limiting potential lateral movement. 3. Monitor network traffic for unusual patterns that may indicate exploitation attempts, such as unexpected configuration changes or anomalous SSID updates. 4. Disable remote management interfaces if not required, reducing the attack surface. 5. Regularly check for vendor firmware updates or advisories addressing this vulnerability and apply patches promptly once available. 6. Employ network intrusion detection/prevention systems (IDS/IPS) with signatures or heuristics capable of detecting exploitation attempts targeting this specific vulnerability. 7. Educate users and administrators about the risks of credential compromise and enforce multi-factor authentication if supported by the device. 8. As a longer-term measure, consider replacing affected devices with models from vendors with a strong security track record and timely patch management.