Firejail before 0.9.44.4, when running on a Linux kernel before 4.8, allows context-dependent attackers to bypass a seccomp-based sandbox protection mechanism via the --allow-debuggers argument.
https://security.gentoo.org/glsa/201701-62
https://github.com/netblue30/firejail/commit/6b8dba29d73257311564ee7f27b9b14758cc693e
https://firejail.wordpress.com/download-2/release-notes/
https://blog.lizzie.io/linux-containers-in-500-loc.html#fn.51