In X.Org X server 20.11 through 21.1.16, when a client application uses easystroke for mouse gestures, the main thread modifies various data structures used by the input thread without acquiring a lock, aka a race condition. In particular, AttachDevice in dix/devices.c does not acquire an input lock.
Exploitability
AV:NAC:HPR:LUI:NScope
S:CImpact
C:LI:LA:H7.7/CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:L/I:L/A:HOther