ProFTPD is open-source FTP server software used on Unix-like systems to provide file transfer services. As a server component, it often runs on systems that must be reachable from the network, which makes it a high-value target when exposed to the internet.
In cyber security, ProFTPD matters because flaws in it can give attackers unauthorized access to files, accounts, or server functions. An example is CVE-2015-3306, an improper access control issue: if permissions are enforced incorrectly, an attacker may be able to perform actions they should not be allowed to do. Defenders look for ProFTPD in asset inventories, restrict unnecessary FTP exposure, keep the service patched, and monitor logs for abuse. Legacy services like FTP are especially risky because they often remain online long after administrators stop actively reviewing them.