PuTTY is a free implementation of Telnet and SSH for Windows and Unix platforms, along with an xterm terminal emulator.
A heap-corrupting buffer overflow bug in the ssh_agent_channel_data function of PuTTY was found.
A remote attacker, utilizing the SSH agent forwarding of an SSH server, could execute arbitrary code with the privileges of the user running the client or cause a Denial of Service condition.
There is no known workaround at this time.
All PuTTY users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=net-misc/putty-0.68"