PuTTY: Pre-authentication arbitrary code execution

Background

PuTTY is a free implementation of Telnet and SSH for Win32 and Unix platforms, along with an xterm terminal emulator.

Description

PuTTY contains a vulnerability allowing a malicious server to execute arbitrary code on the connecting client before host key verification.

Impact

When connecting to a server using the SSH2 protocol an attacker is able to execute arbitrary code with the permissions of the user running PuTTY by sending specially crafted packets to the client during the authentication process but before host key verification.

Workaround

There is no known workaround at this time. All users are encouraged to upgrade to the latest available version of PuTTY.

Resolution

All PuTTY users should upgrade to the latest version:

 # emerge sync
 
 # emerge -pv ">=net-misc/putty-0.55"
 # emerge ">=net-misc/putty-0.55"