Polkit

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. Polkit allows a level of control of centralized system policy. It is developed and maintained by David Zeuthen from Red Hat and hosted by the freedesktop.org project. It is published as free software under the terms of version 2 of the GNU Lesser General Public License.^[3]

polkit
KDE Plasma-based front-end
Developers	David Zeuthen, Red Hat
Initial release	0.3[1]
Stable release	126[2]  / 13 January 2025; 9 months ago (13 January 2025)
Repository	github.com/polkit-org/polkit
Written in	C
Operating system	Linux, Unix-like
Type	Privilege authorization
License	LGPL (free software)
Website	github.com/polkit-org/polkit

Since version 0.105, released in April 2012,^[4][5] the name of the project was changed from PolicyKit to polkit to emphasize that the system component was rewritten^[6] and that the application programming interface had changed, breaking backward compatibility.^{[7][dubious – discuss]}

Fedora became the first distribution to include PolicyKit, and it has since been used in other distributions, including Ubuntu since version 8.04 and openSUSE since version 10.3. Some distributions, like Fedora,^[8] have already switched to the rewritten polkit.

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).^[9] Systemd provides an alternate interface to polkit called run0.

Implementation

The polkitd daemon implements Polkit functionality.^[10]

Security

PwnKit

CVE identifier	CVE-2021-4034
Date discovered	18 November 2021; 3 years ago (2021-11-18)
Discoverer	Qualys Research Team
Affected hardware	All architectures
Affected software	Polkit (all versions prior to discovery)
Used by	Default on every major Linux distribution
Website	qualys.com

Polkit improves on the security offered by sudo by avoiding SUID binaries, which are the primary cause of privilege escalation vulnerabilities on Unix-like systems.^[11]

Nevertheless, as with sudo, several privilege escalation vulnerabilities have been found in polkit. The memory corruption vulnerability PwnKit (CVE-2021-4034^[12]) discovered in the pkexec command (installed on all major Linux distributions) was announced on January 25, 2022.^[13][14] The vulnerability dates back to the original distribution from 2009. The vulnerability received a CVSS score of 7.8 ("High severity") reflecting serious factors involved in a possible exploit: unprivileged users can gain full root privileges, regardless of the underlying machine architecture or whether the polkit daemon is running or not.

See also

• Free and open-source software portal

• Pluggable authentication module
• Principle of least privilege
• PackageKit
• User Account Control – a similar feature introduced in Windows Vista and still exists in Windows 11