mod_sql 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).
Exploitability
AV:NAC:HPR:NUI:NScope
S:UImpact
C:HI:HA:H8.1/CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:HInjection