The (commonly referred to in your query context as "vsftpd 208" due to version naming variations or scanning banner results) is a famous supply chain vulnerability identified as CVE-2011-2523 . It involves a malicious backdoor that was intentionally added to the source code of vsftpd version 2.3.4 between June 30 and July 3, 2011. Core Vulnerability Mechanism
Exploit examples and tools
But with the backdoored version, sending: vsftpd 208 exploit github install