olemus
turbepaik või uus turvafunktsioon

ülevaateid
https://askubuntu.com/questions/27418/what-is-a-security-update

https://www.quora.com/What-is-security-patch-level-Does-security-patch-update-make-any-difference-in-android

https://support.apple.com/en-us/HT201222

https://www.zerodayinitiative.com/blog/2021/10/12/the-october-2021-security-update-review