socket.c in GNU Screen through 4.9.0, when installed setuid or setgid (the default on platforms such as Arch Linux and FreeBSD), allows local users to send a privileged SIGHUP signal to any PID, causing a denial of service or disruption of the target process.
https://www.exploit-db.com/exploits/51252
https://savannah.gnu.org/bugs/?63195
https://git.savannah.gnu.org/cgit/screen.git/patch/?id=e9ad41bfedb4537a6f0de20f00b27c7739f168f7