Common encryption key appears to be used across all deployed instances of Serv-U FTP Server. Because of this an encrypted value that is exposed to an attacker can be simply recovered to plaintext.
https://www.solarwinds.com/trust-center/security-advisories/CVE-2021-35252
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-35252