ArchLinux: 202102-26: firejail: privilege escalation
Summary
Firejail before 0.9.64.4 allows attackers to bypass intended access restrictions because there is a TOCTOU race condition between a stat operation and an OverlayFS mount operation.
Resolution
Upgrade to 0.9.64.4-1.
# pacman -Syu "firejail>=0.9.64.4-1"
The problem has been fixed upstream in version 0.9.64.4.
References
https://unparalleled.eu/publications/2021/advisory-unpar-2021-0.txt https://unparalleled.eu/blog/2021/20210208-rigged-race-against-firejail-for-local-root/ https://github.com/netblue30/firejail/commit/97d8a03cad19501f017587cc4e47d8418273834b https://security.archlinux.org/CVE-2021-26910
Workaround
The issue can be mitigated by setting "overlayfs no" in/etc/firejail/firejail.config.