CVE-2021-4034

Red Hat Polkit Out-of-Bounds Read and Write Vulnerability

High 7.8
Exploited: added to CISA KEV 27 Jun 2022
Used in ransomware campaigns

Description

A local privilege escalation vulnerability was found on polkit's pkexec utility. The pkexec application is a setuid tool designed to allow unprivileged users to run commands as privileged users according predefined policies. The current version of pkexec doesn't handle the calling parameters count correctly and ends trying to execute environment variables as commands. An attacker can leverage this by crafting environment variables in such a way it'll induce pkexec to execute arbitrary code. When successfully executed the attack can cause a local privilege escalation given unprivileged users administrative rights on the target machine.

Key facts

Published: 28 Jan 2022
Last changed: 15 Aug 2026
Assigned by: redhat
KEV added: 27 Jun 2022
KEV fix due: 18 Jul 2022
Used in ransomware: Yes, according to CISA
EPSS: 94.921% likely to be exploited in the next 30 days, higher than 99.862% of CVEs (scores for 15 Nov 2026)
SSVC (CISA): Exploitation: active; Automatable: no; Technical impact: total

Severity scores

Each score is shown as its source gave it. They are not averaged or merged.

7.8CVSS 3.1, Highfrom CISA (ADP container)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

What to do

Apply updates per vendor instructions.CISA KEV required action

Historical context and remediation

This reference retains the original CVE publication date. A recent record update does not mean a new attack occurred.

No separately sourced impact summary is available on this page yet. Consult the description, version data and dated exploitation evidence.

Version statuses below come from the CNA. An “unaffected” version is not necessarily a currently supported release or proof of a patch date. EPSS is a dated risk estimate, not a count of historical attacks.

Read the original CVE record.

Affected products

Vendor	Product	Versions
n/a	polkit	all (affected)