putty version 0.55 released
2004-08-03 SECURITY HOLE, fixed in PuTTY 0.55PuTTY 0.55, released today, fixes a serious security hole which may allow a server to execute code of its choice on a PuTTY client connecting to it. In SSH2, the attack can be performed before host key verification, meaning that even if you trust the server you think you are connecting to, a different machine could be impersonating it and could launch the attack before you could tell the difference. We recommend everybody upgrade to 0.55 as soon as possible.
Putty for windows
http://the.earth.li/~sgtatham/putty/.../x86/putty.exe