[pyftpdlib] Improper Authentication in pyftpdlib

FTPServer.py in pyftpdlib before 0.2.0 does not increment the attempted_logins count for a USER command that specifies an invalid username, which makes it easier for remote attackers to obtain access via a brute-force attack.

References

• https://nvd.nist.gov/vuln/detail/CVE-2007-6737
• https://github.com/giampaolo/pyftpdlib/issues/20
• https://github.com/advisories/GHSA-9×66-ghqx-8g5r