[pyftpdlib] Improper Authentication in pyftpdlib

ftpserver.py in pyftpdlib before 0.5.0 does not delay its response after receiving an invalid login attempt, which makes it easier for remote attackers to obtain access via a brute-force attack.

References

• https://nvd.nist.gov/vuln/detail/CVE-2008-7263
• https://github.com/giampaolo/pyftpdlib/issues/73
• https://github.com/advisories/GHSA-q6w2-jxcm-2crj