Firejail before 0.9.60 allows truncation (resizing to length 0) of the firejail binary on the host by running exploit code inside a firejail sandbox and having the sandbox terminated. To succeed, certain conditions need to be fulfilled: The jail (with the exploit code inside) needs to be started as root, and it also needs to be terminated as root from the host (either by stopping it ungracefully (e.g., SIGKILL), or by using the --shutdown control command). This is similar to CVE-2019-5736.
A Privilege Context Switching issue was discovered in join.c in Firejail 0.9.68. By crafting a bogus Firejail container that is accepted by the Firejail setuid-root program as a join target, a local attacker can enter an environment in which the Linux user namespace is still the initial user namespace, the NO_NEW_PRIVS prctl is not activated, and the entered mount namespace is under the attacker's control. In this way, the filesystem layout can be adjusted to gain root privileges through execution of…
security update
Firejail uses weak permissions for /dev/shm/firejail and possibly other files, which allows local users to gain privileges.