In manager.c in ss-manager in shadowsocks-libev 3.1.0, improper parsing allows command injection via shell metacharacters in a JSON configuration request received via 127.0.0.1 UDP traffic, related to the add_server, build_config, and construct_command_line functions.
https://github.com/shadowsocks/shadowsocks-libev/issues/1734
https://github.com/shadowsocks/shadowsocks-libev/commit/c67d275803dc6ea22c558d06b1f7ba9f94cd8de3