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.
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.