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             AUSCERT External Security Bulletin Redistribution

                      USN-4728-1: snapd vulnerability
                             10 February 2021


        AusCERT Security Bulletin Summary

Product:           snapd
Publisher:         Ubuntu
Operating System:  Ubuntu
                   Linux variants
Impact/Access:     Increased Privileges -- Existing Account
Resolution:        Patch/Upgrade
CVE Names:         CVE-2020-27352  

Original Bulletin: 

Comment: This advisory references vulnerabilities in products which run on 
         platforms other than Ubuntu. It is recommended that administrators 
         running snapd check for an updated version of the software for their
         operating system.

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USN-4728-1: snapd vulnerability
10 February 2021

An intended access restriction in snapd could be bypassed by container
management snaps.

  o Ubuntu 20.10
  o Ubuntu 20.04 LTS
  o Ubuntu 18.04 LTS
  o Ubuntu 16.04 LTS


  o snapd - Daemon and tooling that enable snap packages


Gilad Reti discovered that snapd did not correctly specify cgroup
delegation when generating systemd service units for various container
management snaps. This could allow a local attacker to escalate privileges
via access to arbitrary devices of the container host from within a
compromised or malicious container.

Update instructions

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

Ubuntu 20.10

  o snapd - 2.48.3+20.10

Ubuntu 20.04

  o snapd - 2.48.3+20.04

Ubuntu 18.04

  o snapd - 2.48.3+18.04

Ubuntu 16.04

  o snapd - 2.48.3

In general, a standard system update will make all the necessary changes.
On Ubuntu, snapd will automatically refresh itself to snapd 2.48.3 which is
unaffected. Affected container management snaps will also automatically
refresh which will restart containers and resolve this vulnerability.


  o CVE-2020-27352

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