3proxy 0.5 to 0.5.2, when NT-encoded passwords are being used, allows remote attackers to cause a denial of service (blocked account) via unspecified vectors related to NTLM authentication, which causes a password hash to be overwritten.

3proxy 0.5 to 0.5.2 does not offer NTLM authentication before basic authentication, which might cause browsers with incomplete RFC2616/RFC2617 support to use basic cleartext authentication even if NTLM is available, which makes it easier for attackers to steal credentials.

Double free vulnerability in the ftpprchild function in ftppr in 3proxy 0.5 through 0.5.3i allows remote attackers to cause a denial of service (daemon crash) via multiple OPEN commands to the FTP proxy.