See how proftpd compares to other vendors in security performance
modsql in ProFTPD before 1.3.9a allows remote attackers to execute arbitrary code via a username, in scenarios where there is logging of USER requests with an expansion such as %U, and the SQL backend allows commands (e.g., COPY TO PROGRAM).
ProFTPD contains an improper access control vulnerability that could allow remote attackers to read and write to arbitrary files via the site cpfr and site cpto commands.