========================================================================== Ubuntu Security Notice USN-4424-1 July 15, 2020 snapd vulnerabilities ========================================================================== A security issue affects these releases of Ubuntu and its derivatives: - Ubuntu 20.04 LTS - Ubuntu 19.10 - Ubuntu 18.04 LTS - Ubuntu 16.04 LTS Summary: An intended access restriction in snapd could be bypassed by strict mode snaps. Software Description: - 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 LTS: snapd 2.45.1+20.04.2 Ubuntu 19.10: snapd 2.45.1+19.10.2 Ubuntu 18.04 LTS: snapd 2.45.1+18.04.2 Ubuntu 16.04 LTS: 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: https://usn.ubuntu.com/4424-1 CVE-2020-11933, CVE-2020-11934 Package Information: https://launchpad.net/ubuntu/+source/snapd/2.45.1+20.04.2 https://launchpad.net/ubuntu/+source/snapd/2.45.1+19.10.2 https://launchpad.net/ubuntu/+source/snapd/2.45.1+18.04.2 https://launchpad.net/ubuntu/+source/snapd/2.45.1ubuntu0.2