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Ubuntu Security Notice USN-5141-1
November 11, 2021

firejail vulnerability
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 20.04 LTS

Summary:

Firejail could be made to overwrite files as the administrator.

Software Description:
- firejail: Application sandbox

Details:

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.

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 20.04 LTS:
  firejail                        0.9.62-3ubuntu0.1

In general, a standard system update will make all the necessary changes.

References:
  https://ubuntu.com/security/notices/USN-5141-1
  CVE-2021-26910

Package Information:
  https://launchpad.net/ubuntu/+source/firejail/0.9.62-3ubuntu0.1