Key excerpt/context from the advisory:

We discovered a Local Privilege Escalation (from any user to root) in polkit's pkexec, a SUID-root program that is installed by default on every major Linux distribution:

"Polkit (formerly PolicyKit) is a component for controlling system-wide privileges in Unix-like operating systems. It provides an organized way for non-privileged processes to communicate with privileged ones. [...] It is also possible to use polkit to execute commands with elevated privileges using the command pkexec followed by the command intended to be executed (with root permission)." (Wikipedia)

This vulnerability is an attacker's dream come true:

- pkexec is installed by default on all major Linux distributions (we exploited Ubuntu, Debian, Fedora, CentOS, and other distributions are probably also exploitable);

- pkexec is vulnerable since its creation, in May 2009 (commit c8c3d83, "Add a pkexec(1) command");

- any unprivileged local user can exploit this vulnerability to obtain full root privileges;

- although this vulnerability is technically a memory corruption, it is exploitable instantly, reliably, in an architecture-independent way;

- and it is exploitable even if the polkit daemon itself is not running.

Looks like https://news.ycombinator.com/item?id=30077271 got more traction.

this one seems about as good as sequoia CVE.

score yet another big one for open sores!