When executing a program via the bubblewrap sandbox, the nonpriv session can escape to the parent session by using the TIOCSTI ioctl to push characters into the terminal's input buffer, allowing an attacker to escape the sandbox.

References:

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=850702

Upstream bugs:

https://github.com/projectatomic/bubblewrap/issues/142 https://github.com/projectatomic/bubblewrap/pull/143

Upstream patch:

https://github.com/projectatomic/bubblewrap/commit/d7fc532c42f0e9bf427923bab85433282b3e5117