Ubuntu Security Notice 4424-1 - 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. 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. Various other issues were also addressed.
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