All versions of ftp-srv from v1.0.0 onward to v4.3.3 are vulnerable to Server-Side Request Forgery (SSRF). The package fails to prevent remote clients to access other resources in the network, for example when connecting to the server through telnet. This allows attackers to access any network resources available to the server, including private resources in the hosting environment.
Recommendation
Upgrade to patched versions
^2.19.6, ^3.1.2, ^4.3.4
Workarounds
Blacklisting the FTP Command PORT will prevent the server from exposing this behaviour through active connections until a fix is applied.
const ftp = new FtpSrv({
blacklist: ['PORT']
});