Recently a Linux kernel vulnerability (CVE-2021-22555), which allows for possible privilege escalation, was announced . While Aptible Deploy is not impacted by the published exploits, we will still be taking steps to prevent any potential future exploits of this vulnerability.
As part of our remediation efforts, we will be restarting all App, Bastion, and Build instances in shared stacks today. This will involve restarting Bastion and Build instances, which may result in a small number of operation failures and a short disruption to outbound traffic. Operations which fail due to this outage should work on retry. App restarts will be done using Aptible's zero-downtime release process . As a result, you should not see any impact from these restarts.
Notifications for the patching schedule for dedicated stacks will also be sent out today (July 16).