Yes, actual threat actors use these techniques even after publication. There is a lot of outdated/misconfigured systems in the wild. A fairly recent example is the defacing of multiple Ukrainian government websites[1], through exploiting a vulnerability fixed and publicised in august 2021. There's also around 10,000 (can't remember where that statistic is from) Huawei routers on the internet vulnerable to an issue from 2015, which are constantly being infected with botnet worms.

[1] https://www.bleepingcomputer.com/news/security/multiple-ukra...