A buffer overflow exists in the filename parameter of the formFtpServerDirConfig function within UTT Aggressive 520W firmware v3v1.7.7-180627. By sending a specially crafted filename through the FTP service, an attacker can corrupt memory and force the service to crash, resulting in a denial‑of‑service condition.

The vulnerability affects only UTT Aggressive 520W routers running firmware v3v1.7.7-180627. No other vendors or product variations are reported to be impacted.

Specific CVSS or EPSS scores are not provided, and the vulnerability does not appear in any known exploited vulnerability catalog. The attack can be launched remotely by an attacker who can reach the device’s FTP port. While it does not provide further system compromise, it can disrupt network operations by causing the FTP service to stop, which may be significant in environments where the router is exposed to untrusted networks.