A serious memory corruption vulnerability in polkit (formerly PolicyKit) has finally been discovered after 12+ years. This program is found in essentially all modern Linux distributions.
The most likely attack scenario is from an internal threat where a malicious user can escalate from no privileges whatsoever to full root privileges. From an external threat perspective, if an attacker has been able to gain foothold on a system via another vulnerability or a password breach, that attacker can then escalate to full root privileges through this vulnerability.
So ‘pkexec’ is basically ‘sudo’ but instead of depending on PAM it uses polikit for authentication and authorization. How many ‘sudo’ programs do we need in one Linux system? :D