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Published: 08 February 2021

Firejail before allows attackers to bypass intended access restrictions because there is a TOCTOU race condition between a stat operation and an OverlayFS mount operation.

From the Ubuntu security team

Roman Fiedler discovered that a race condition existed in Firejail when using OverlayFS to prevent writes to the underlying file system. A local attacker could use this to gain administrative privileges. Note: this update disables support for OverlayFS in Firejail.



CVSS 3 base score: 7.0


Package Release Status
Launchpad, Ubuntu, Debian
Released (
Ubuntu 21.10 (Impish Indri) Not vulnerable
Ubuntu 21.04 (Hirsute Hippo) Not vulnerable
Ubuntu 20.04 LTS (Focal Fossa)
Released (0.9.62-3ubuntu0.1)
Ubuntu 18.04 LTS (Bionic Beaver) Needs triage

Ubuntu 16.04 ESM (Xenial Xerus) Ignored
(end of standard support, was needs-triage)
Ubuntu 14.04 ESM (Trusty Tahr) Does not exist