lshell 0.9.16 allows remote authenticated users to break out of a limited shell and execute arbitrary commands.
https://github.com/ghantoos/lshell/pull/153/commits/a686f71732a3d0f16df52ef46ab8a49ee0083c68
https://github.com/ghantoos/lshell/issues/149
https://github.com/ghantoos/lshell/commit/e72dfcd1f258193f9aaea3591ecbdaed207661a0
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=834946