Linux vendors on Tuesday issued patches for a memory corruption vulnerability in a component called polkit that allows an unprivileged logged-in user to gain full root access on a system in its default configuration.
Security vendor Qualys found the flaw and published details in a coordinated disclosure.
Polkit, previously known as PolicyKit, is a tool for setting up policies governing how unprivileged processes interact with privileged ones. The vulnerability resides within polkit’s pkexec, a SUID-root program that’s installed by default on all major Linux distributions. Designated CVE-2021-4034, the vulnerability has been given a CVSS score of 7.8.
Bharat Jogi, director of vulnerability and threat research at Qualys, explained in a blog post that the pkexec flaw opens the door to root privileges for an attacker. Qualys researchers, he said, have demonstrated exploitation on default installations of Ubuntu, Debian, Fedora, and CentOS, and other Linux distributions are presumed to be vulnerable as well.