PwnKit (CVE-2021-4034).

A local privilege-escalation vulnerability in the Polkit pkexec utility that lets any unprivileged user gain root on most Linux distributions. It belongs to the Vulnerabilities category of cybersecurity.

A local privilege-escalation vulnerability in the Polkit pkexec utility that lets any unprivileged user gain root on most Linux distributions.

PwnKit, tracked as CVE-2021-4034, is a memory-corruption flaw disclosed by Qualys in January 2022 in pkexec, a SUID-root binary shipped with Polkit and present by default on virtually every major Linux distribution since 2009. By invoking pkexec with no arguments, an attacker can craft environment variables that are reintroduced into the process after argv handling, allowing arbitrary code execution as root. The bug requires only local shell access, has reliable public exploits, and works on Ubuntu, Debian, RHEL, CentOS, Fedora and others. Mitigation is patching pkexec or removing its SUID bit until updates are applied.

Defences for PwnKit (CVE-2021-4034) typically combine technical controls and operational practices, as detailed in the full definition above.

Common alternative names include: CVE-2021-4034, Polkit pkexec LPE.