The PwnKit vulnerability is a high-severity bug in Polkit, a component used to control privileges in Unix-like operating systems, which has existed since 2009 and was recently discovered by a security researcher. The vulnerability allows an attacker to corrupt memory through a buffer overflow, leading to full root privileges on the target host. It is caused by a flaw in command line argument handling and can be exploited when the `pkexec` command is run without arguments, resulting in corrupted memory. Patches have been made available quickly, and it is recommended to install operating system updates immediately or remove the SUID bit from `pkexec` manually. The vulnerability affects many major Linux distributions, including Red Hat, Ubuntu, and SUSE, and highlights the importance of keeping up-to-date with security patches.