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AUSCERT External Security Bulletin Redistribution
ESB-2020.2415
USN-4424-1: snapd vulnerabilities
16 July 2020
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AusCERT Security Bulletin Summary
---------------------------------
Product: snapd
Publisher: Ubuntu
Operating System: Ubuntu
Linux variants
Impact/Access: Reduced Security -- Unknown/Unspecified
Unauthorised Access -- Console/Physical
Resolution: Patch/Upgrade
CVE Names: CVE-2020-11934 CVE-2020-11933
Original Bulletin:
https://usn.ubuntu.com/4424-1/
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-4424-1: snapd vulnerabilities
15 July 2020
snapd vulnerabilities
Releases
o Ubuntu 20.04 LTS
o Ubuntu 19.10
o Ubuntu 18.04 LTS
o Ubuntu 16.04 LTS
Packages
o snapd - Daemon and tooling that enable snap packages
Details
It was discovered that cloud-init as managed by snapd on Ubuntu Core 16 and
Ubuntu Core 18 devices ran on every boot without restrictions. A physical
attacker could exploit this to craft cloud-init user-data/meta-data via
external media to perform arbitrary changes on the device to bypass
intended security mechanisms such as full disk encryption. This issue did
not affect traditional Ubuntu systems. (CVE-2020-11933)
It was discovered that snapctl user-open allowed altering the XDG_DATA_DIRS
environment variable when calling the system xdg-open. A malicious snap
could exploit this to bypass intended access restrictions to control how
the host system xdg-open script opens the URL. This issue did not affect
Ubuntu Core systems. (CVE-2020-11934)
Update instructions
The problem can be corrected by updating your system to the following package
versions:
Ubuntu 20.04
o snapd - 2.45.1+20.04.2
Ubuntu 19.10
o snapd - 2.45.1+19.10.2
Ubuntu 18.04
o snapd - 2.45.1+18.04.2
Ubuntu 16.04
o snapd - 2.45.1ubuntu0.2
In general, a standard system update will make all the necessary changes.
On Ubuntu, snapd will automatically refresh itself to snapd 2.45.2 which
is unaffected.
References
o CVE-2020-11933
o CVE-2020-11934
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