Summary
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)
Fixed packages 3
| Release | Package | Fixed in |
|---|---|---|
| Ubuntu · 16.04 LTS 16.04:LTS | snapd | 2.45.1ubuntu0.2 |
| Ubuntu · 18.04 LTS 18.04:LTS | snapd | 2.45.1+18.04.2 |
| Ubuntu · 20.04 LTS 20.04:LTS | snapd | 2.45.1+20.04.2 |
Vulnerabilities 1
-
Medium 5.9
Sandbox escape vulnerability via snapctl user-open (xdg-open)
It was discovered that snapctl user-open allowed altering the $XDG_DATA_DIRS environment variable when calling the system xdg-open. OpenURL() in usersession/userd/launcher.go would alter $XDG_DATA_DIRS to append a path to a directory controlled by the calling…