How do I apply an installed, but not running, security update to Amazon Linux 2023?

Question

I just started using Amazon Linux 2023. When I connect by SSH, I get this notice:
```
Updates Information Summary: available
    1 Security notice(s)
        1 Important Security notice(s)
Security: kernel-6.1.55-75.123.amzn2023.x86_64 is an installed security update
Security: kernel-6.1.52-71.125.amzn2023.x86_64 is the currently running version
```

How do I apply the installed update? I tried rebooting the instance in the console and that didn't do anything. It's unfortunate that the notice doesn't tell me how to fix it. I'm inclined to just ignore it because it's not obvious what to do, but that's surely not what Amazon hopes users will do?

Answer

Usually, it means a new kernel has been applied and you need to reboot.
If your `uname -a` output contains the string `6.1.55-75.123.amzn2023`, you are good.

This observation has been logged into AL2023 GitHub under [update-motd not run after dnf upgrade #441](https://github.com/amazonlinux/amazon-linux-2023/issues/441). From the description, it seems that running `sudo update-motd` can help.

Answer

I suppose it's temporarily moot because I have a new update notice:
```
A newer release of "Amazon Linux" is available.
  Version 2023.2.20231011:
Run "/usr/bin/dnf check-release-update" for full release and version update info
```

Which fortunately does provide instruction on what to do.

But the thing is I did use the "Reboot" function of EC2, at a guess. But the notice in the OP remained. Unless that function doesn't really do a full reboot? It does have the version string you mentioned with `uname -a` though.

The message I saw isn't the same as that one though, so I'm not sure it's the same issue?

How do I apply an installed, but not running, security update to Amazon Linux 2023?

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