A stack-based buffer overflow exists in the formFilter function of TOTOLINK A3002RU V2.1.1-B20211108.1455, triggered when an attacker supplies overly long values for the vpnUser or vpnPassword parameters. The overflow can corrupt the execution stack and potentially allow arbitrary code execution on the device, compromising confidentiality, integrity, and availability of the router and any connected networks. The weakness is a classic buffer overflow flaw (CWE-121/CWE-787).

TOTOLINK A3002RU model operated with firmware version 2.1.1-B20211108.1455 is affected. No other products or versions are listed as impacted.

The vulnerability has a CVSS score of 8.8, indicating high severity, but the EPSS score is below 1%, suggesting a very low probability of exploitation in the wild at this time. It is not listed in the CISA KEV catalog. Attackers would likely exploit the flaw remotely via HTTP requests to the router’s web interface, as the vulnerable parameters are transmitted through the formFilter endpoint. No public exploit has been reported, so the risk remains theoretical until an attacker demonstrates a working exploit.