The last Serv-U release notes which mention OpenSSL were from version 12.1.0.6 indicating OpenSSL 0.9.8x.
Does Serv-U version 15.x still use OpenSSL 0.9.8x or has that been updated?
I'm concerned if our Serv-U installation is affected by CVE-2014-0160, HeartBleed OpenSSL vulnerability, which is a nasty one. OpenSSL versions 1.0.1 through 1.0.1f (inclusive) are vulnerable.