CVE-2025-60336 is a vulnerability identified in the TOTOLINK N600R router, specifically in firmware version 4.3.0cu.7866_B20220506. The flaw is a NULL pointer dereference occurring in the sub_41773C function, which is triggered by processing a specially crafted HTTP request. This causes the router's software to attempt to access memory through a NULL pointer, resulting in a crash or reboot of the device, effectively causing a Denial of Service (DoS). The vulnerability is remotely exploitable over the network without requiring any authentication or user interaction, making it accessible to any attacker who can reach the router's HTTP management interface. The CVSS v3.1 score of 7.5 reflects the high impact on availability, with no impact on confidentiality or integrity. Although no exploits have been reported in the wild yet, the vulnerability's nature and ease of exploitation pose a significant risk to network stability. The affected device is commonly used in small to medium-sized business and home environments, where disruption could impact internet connectivity and internal network operations. The absence of a patch at the time of disclosure necessitates interim mitigation strategies to reduce exposure. This vulnerability is classified under CWE-476 (NULL Pointer Dereference), a common programming error that can lead to crashes and service outages.

For European organizations, the primary impact of CVE-2025-60336 is the potential for network outages caused by router crashes. This can disrupt business operations, especially for organizations relying on TOTOLINK N600R routers for internet access or internal network routing. Critical services dependent on continuous connectivity, such as VoIP, cloud applications, and remote work infrastructure, may be interrupted. The vulnerability does not compromise data confidentiality or integrity but poses a significant availability risk. In sectors like healthcare, finance, and public administration, even short-term network downtime can have severe operational and regulatory consequences. Additionally, the vulnerability could be leveraged as part of a broader attack to cause disruption or as a denial-of-service vector against targeted organizations. Given the remote and unauthenticated nature of the exploit, attackers can easily scan for vulnerable devices and launch attacks at scale, potentially affecting multiple organizations simultaneously.

1. Monitor TOTOLINK’s official channels for firmware updates addressing this vulnerability and apply patches promptly once available. 2. Restrict access to the router’s HTTP management interface by implementing network segmentation and firewall rules that limit access to trusted IP addresses only. 3. Disable remote management features if not required, or enforce strong access controls such as VPN-only access for management interfaces. 4. Employ network intrusion detection/prevention systems (IDS/IPS) to detect and block suspicious HTTP requests targeting the router. 5. Regularly audit network devices to identify and inventory TOTOLINK N600R routers to assess exposure. 6. Consider deploying redundant network paths or failover mechanisms to maintain connectivity in case of device failure. 7. Educate network administrators on monitoring router logs for unusual crashes or reboots that may indicate exploitation attempts. 8. If feasible, replace affected devices with models from vendors with a stronger security track record or better update support.