CVE-2025-55586 is a buffer overflow vulnerability identified in the TOTOLINK A3002R router firmware version 4.0.0-B20230531.1404. The vulnerability exists in the handling of the 'url' parameter at the endpoint /boafrm/formFilter. A buffer overflow occurs when the input data exceeds the allocated buffer size, potentially overwriting adjacent memory. In this case, an attacker can craft a specially designed input to the 'url' parameter that triggers the overflow, causing the device to crash or become unresponsive, resulting in a Denial of Service (DoS) condition. This vulnerability does not appear to allow remote code execution or privilege escalation based on the available information, but it does impact the availability of the device. The vulnerability requires sending a malicious HTTP request to the affected endpoint, which is typically accessible on the local network or possibly remotely if the device's management interface is exposed. No authentication or user interaction is indicated as necessary for exploitation, increasing the risk. No known exploits are reported in the wild, and no official patches or mitigations have been published yet. The absence of a CVSS score means the severity must be assessed based on the impact and exploitability factors.

For European organizations using TOTOLINK A3002R routers, this vulnerability could lead to network outages or degraded service availability if exploited. The DoS condition could disrupt internet connectivity, internal network communications, or access to critical services relying on the router. This is particularly impactful for small and medium enterprises or branch offices that depend on these routers for network access. Additionally, if the device is used in critical infrastructure or sensitive environments, the loss of availability could have cascading effects on operational continuity. Since the vulnerability can be triggered remotely if the management interface is exposed, attackers could leverage this to disrupt services without physical access. The lack of authentication requirement increases the threat surface. However, the impact is limited to availability and does not directly compromise confidentiality or integrity based on current information.

Organizations should immediately audit their network to identify the presence of TOTOLINK A3002R routers running the vulnerable firmware version 4.0.0-B20230531.1404. If found, restrict access to the router management interface by implementing network segmentation and firewall rules to limit access to trusted administrators only. Disable remote management interfaces if not required. Monitor network traffic for unusual HTTP requests targeting /boafrm/formFilter and implement intrusion detection/prevention rules to block suspicious payloads. Since no official patch is currently available, consider temporary mitigation by upgrading to a newer firmware version if available or replacing the device with a more secure alternative. Regularly check for vendor advisories and apply patches promptly once released. Additionally, maintain backups of router configurations to enable rapid recovery in case of a DoS event.