Operating systems must be supported by the vendor which means regular security updates must be provided in order to fix security issues.
Whilst every effort is made to provide the most up-to-date information, you should always check the vendor site for the support status of your particular operating system.
The below will appear on the Refined page at ChromeOS
Vendor : GoogleOperating system name : ChromeOS
Version/Edition : Stable 119
Update policy : Chrome updates happen automatically and without notification every few weeks (currently 4 weeks for the Stable version). You do not need to do anything for the device to update.
Most devices will be updated at the same time regardless of which company made them.
How to check your version :
Click the status area at the lower-right of the bottom of the screen.
Click Settings.
Click About Chrome OS.
Chrome OS version will be listed.
End of Security Updates : Versions of ChromeOS fall out of support on the Auto Update Expiration date. See website for details.
Vendor information:
https://chromiumdash.appspot.com/schedule