A memory corruption vulnerability (CVE-2021-4034) in PolKit, a component used in major Linux distributions and some Unix-like operating systems, can be easily exploited by local unprivileged users to gain full root privileges.

https://blog.qualys.com/vulnerabilities-threat-research/2022/01/25/pwnkit-local-privilege-escalation-vulnerability-discovered-in-polkits-pkexec-cve-2021-4034

Patch for Ubuntu is Available

https://ubuntu.com/security/notices/USN-5252-1

If you don’t have any patch please remove suid bit from pxexec tool with this command

chmod 0755 /usr/bin/pkexec