The SPDY implementation in the ngx_http_spdy_module module in nginx 1.5.10 before 1.5.11, when running on a 32-bit platform, allows remote attackers to execute arbitrary code via a crafted request.
http://www.securitytracker.com/id/1030150
http://mailman.nginx.org/pipermail/nginx-announce/2014/000132.html