Putty is vulnerable to buffer overflow. The ssh_agent_channel_data function in PuTTY allows remote attackers to have unspecified impact via a large length value in an agent protocol message and leveraging the ability to connect to the Unix-domain socket representing the forwarded agent connection, which trigger a buffer overflow.
lists.opensuse.org/opensuse-updates/2017-03/msg00055.html
www.chiark.greenend.org.uk/~sgtatham/putty/wishlist/vuln-agent-fwd-overflow.html
www.securityfocus.com/bid/97156
www.securitytracker.com/id/1038067
git.tartarus.org/?p=simon/putty.git;a=commitdiff;h=4ff22863d895cb7ebfced4cf923a012a614adaa8
security.gentoo.org/glsa/201703-03
security.gentoo.org/glsa/201706-09
www.exploit-db.com/exploits/42137/