2015-02-28 PuTTY 0.64 released, fixing a SECURITY HOLE
PuTTY 0.64, released today, fixes a security hole in 0.63 and before: private-key-not-wiped-2. Also diffie-hellman-range-check has been argued to be a security hole. In addition to these and other less critical bug fixes, 0.64 also supports the major new feature of sharing an SSH connection between multiple instances of PuTTY and its tools, and a command-line and config option to specify the expected host key(s).