drivers/tty/n_tty.c in the Linux kernel before 4.14.11 allows local attackers (who are able to access pseudo terminals) to hang/block further usage of any pseudo terminal devices due to an EXTPROC versus ICANON confusion in TIOCINQ.
Exploitability
AV:LAC:LPR:LUI:NScope
S:UImpact
C:NI:NA:L3.3/CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L