Today we are announcing that the Amazon Linux kernel-default AWS Systems Manager (SSM) parameter will now update to point to the latest Amazon Linux kernel version as new kernel versions get released. On August 17, 2026, for Amazon Linux 2023 (AL2023), the SSM parameter was updated from kernel 6. As new kernel versions get released (expected annually), the parameter will continue to update to the latest kernel version after a validation period. This post explains the default kernel behavior, what it means for your workloads, and how to manage the transition.
Amazon Linux ships multiple kernel versions and has tracked a default kernel for each OS version. For example, the AL2023 parameter: has remained on kernel 6. Going forward, the kernel-default SSM parameter will update to the latest kernel as new versions are released. Each new kernel will go through a 3- to 6-month validation period after GA before we update the default . This window gives you time to test the new kernel before the change. We will announce the kernel-default upgrade date before it takes effect.
Note: Already-running instances will keep the kernel they booted with and are not affected by this change. Only new instances launched from the kernel-default parameter will boot kernel 6. If you already use a version-specific SSM parameter, nothing changes for you. The Linux kernel is the foundation of workloads you run on Amazon Elastic Compute Cloud (Amazon EC2) and other services. Each new kernel brings meaningful improvements. 18 includes the Earliest Eligible Virtual Deadline First (EEVDF) CPU scheduler for fairer CPU time distribution and improved latency in mixed workloads.
The kernel also increases Transmission Control Protocol (TCP) receive buffer for better network throughput on high-bandwidth instances. Previously, customers who wanted to run the latest Amazon Linux kernel had to manually update their SSM parameter references and redeploy each time a new kernel became available. With this change, you can receive these improvements without needing to manually upgrade. Staying on the default kernel is the recommended approach as it allows your new instances to always run the latest validated kernel with no manual intervention.