Recently a major security vulnerability was discovered in Polkit, essentially all Linux systems (since May 2009, yes 2009) that have shell access are exploitable to get root
access. Exploit works almost instantly.
So, if a number of people have shell access to the servers.
Or monitor such vulnerabilities & patch them ASAP, they become a center of attention for hackers who tend to construct multistage exploits, and in combination with almost any remote execution which gives user shell access (like recent log4j
CVE-2021-44228), it becomes remote root execution. It is better to await patch/update ASAP.
The initial source of the security information was a Qualys security company report: