Skip to content
EXYS
Back to the CVEs

CVE-2021-4034

7.8, high Known exploited Used in ransomware

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

NVD (opens in a new tab) CVE.org (opens in a new tab) CISA KEV catalogue (opens in a new tab)
CVSS
7.8, high high CVSS v3.1
EPSS, next 30 days
95% higher than 99.8% of scored CVEs
Exploitation
Confirmed in the wild
Published
28 Jan 20224 years ago

Known exploited

CISA added this to the Known Exploited Vulnerabilities Catalog on 27 Jun 2022 and links it to ransomware activity. US federal agencies had to remediate by 18 Jul 2022, a deadline that has passed.

Required action. Apply updates per vendor instructions.

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.

Details

Vendor
Red Hat and 6 more
Product
polkit
Weakness
CWE-787 (opens in a new tab)
Status
Analyzed
Updated
15 Aug 2026
Assigner
secalert@redhat.com

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

References 13

Exploit code 5

Patches and fixes 3

Advisories 4

Other references 1

The kind is read from NVD's tags where present and from the shape of the URL otherwise, so treat it as a hint.

Other Red Hat CVEs

Every Red Hat CVE we hold

Same vendor in what we hold, not a known link between the flaws.

  • CVE-2021-3560 Red Hat Polkit Incorrect Authorization Vulnerability KEV EPSS 24% 7.8, high
  • CVE-2018-14667 Red Hat JBoss RichFaces Framework Expression Language Injection Vulnerability KEV EPSS 74% 9.8, critical
  • CVE-2017-12149 Red Hat JBoss Application Server Remote Code Execution Vulnerability KEV EPSS 91% 9.8, critical
  • CVE-2015-5287 Red Hat Automatic Bug Reporting Tool Privilege Escalation Vulnerability KEV EPSS 5% 7.8, high
  • CVE-2015-3246 Red Hat Libuser Race Condition Vulnerability KEV EPSS 9% 7.4, high
  • CVE-2010-1871 Red Hat Linux JBoss Seam 2 Remote Code Execution Vulnerability KEV EPSS 83% 8.8, high
  • CVE-2010-0738 Red Hat JBoss Authentication Bypass Vulnerability KEV EPSS 75% 5.3, medium
  • CVE-2010-1428 Red Hat JBoss Information Disclosure Vulnerability KEV EPSS 61% 7.5, high

Beyond this page

Is CVE-2021-4034 in your network?

This page tells you how dangerous CVE-2021-4034 is out there. Whether it sits on one of your devices, only a scan of your own network can tell. That is what our systems do, every day, for the companies we protect.

CVE-2021-4034 is in the CISA catalogue of exploited vulnerabilities: attackers are already exploiting it.

  • EXYS7600 OCELOT

    Find it before attackers do

    Ocelot scans your network on a schedule and reports every vulnerability it finds by its CVE identifier, with its CVSS score and how many of your hosts are affected. A finding like CVE-2021-4034 comes with the devices to patch.

    Learn more about EXYS7600 OCELOT

  • EXYS7950 KONDRA

    Detect it if it's exploited

    Until the patch is applied, Kondra monitors your network, events and endpoints in real time. It keeps an inventory of the software installed on every endpoint, and its anomaly detection rules flag what an attacker does once inside.

    Learn more about EXYS7950 KONDRA
Check your exposure

Assembled from the NVD 2.0 API, the CISA Known Exploited Vulnerabilities Catalog and FIRST EPSS. Scores are as of our last collection on 17 Oct 2026, not the live upstream state.