Long(est) security update support for stable GNU/Linux distributions?

Which *a)* FLOSS *b)* stable (= not rolling release) *c)* desktop GNU/Linux distributions have a *long* security update support? Of course it’s interesting which distro has the *longest* support, but 2nd, 3rd etc. places should be considered, too. **Debian stable** versions get security updates for [around 1 year after the new stable](https://unix.stackexchange.com/a/96137/21962) version is released. *In theory* this could be a long time, but you can’t know for sure, can you? **Ubuntu LTS** versions get security updates for [5 years](https://wiki.ubuntu.com/LTS) . Any distro offers more?