# What is CVE-2021-4034?

> CVE-2021-4034 is a high-severity flaw (CVSS 7.8) in Polkit from Polkit Project, published on 28 January 2022. It is on the list of flaws known to be exploited, so criminals are already using it. The latest forecast puts its chance of use in the next 30 days at 95%. If you run an affected version, patch it first.

Canonical page: https://www.precursorintelligence.com/what-is/cve-2021-4034

## At a glance

- **Verdict:** Fix this now. Attackers are using this flaw today. If you run an affected version, it goes to the top of your list.
- **Precursor Intelligence risk score:** 80 out of 100 (High); action: Emergency patch. Kept up to date as the evidence changes.
- **Severity:** High (CVSS 7.8 out of 10)
- **Known to be exploited:** Yes, it is on the government list of flaws known to be exploited
- **Chance of use in the next 30 days:** 95% (latest exploit-likelihood forecast)
- **Published:** 28 January 2022
- **Record last updated:** 6 November 2025
- **Main product:** Polkit from Polkit Project
- **Affected products:** 30

## What is CVE-2021-4034? In plain terms

An attacker has to be already on the device with an ordinary user account, and nobody has to click anything. If it works, the attacker can read data, change data and take it offline.

### The official 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.

### What kind of flaw is it?

- CWE-787: Out-of-bounds Write
- CWE-125: Out-of-bounds Read

### How an attack on it works

- Where an attacker can be: Already on the device
- How hard it is to pull off: Easy: no special conditions
- Login needed first: An ordinary user account
- Does someone have to click: No, nobody has to do anything
- What an attacker gets: Can read data, change data and take it offline

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

## Is CVE-2021-4034 being exploited? Yes

Attackers are already using it. It is on the government list of flaws known to be exploited, and the latest forecast puts the chance of it being used in the next 30 days at 95%.

Exploit likelihood over the last 7 days: 94%, 95%, 95%, 95%, 95%, 95%, 95%.

### Timeline

- 28 January 2022: Published
- 6 November 2025: Record last updated

### How Precursor Intelligence ranks it

CVE-2021-4034 scores **80 out of 100 (High)**, with the action "Emergency patch".

Every published flaw gets a risk score from 0 to 100, kept up to date as the evidence changes. Four things go into the score, from the one that counts most to the ones that count less:

- Evidence it is being exploited: biggest factor
- How severe it is: strong factor
- How widely exposed it is: smaller factor
- Threat activity around it: smaller factor

85 and above is Critical. Anything confirmed as exploited is always marked for an emergency patch, whatever its score. When this flaw matches software you track, it lands in your list with its score and the reasons behind it.

## Who is affected by CVE-2021-4034?

The published record lists 30 products. Versions are as published: "before 121" means every version up to, but not including, 121.

- [Polkit](https://www.precursorintelligence.com/product/polkit_project/polkit) by [Polkit Project](https://www.precursorintelligence.com/vendors/polkit_project) (Application): before 121
- [Enterprise Linux Server Aus](https://www.precursorintelligence.com/product/redhat/enterprise_linux_server_aus) by [Red Hat](https://www.precursorintelligence.com/vendors/redhat) (Operating system): 7.3, 7.4, 7.6, 7.7, 8.2, 8.4
- [Enterprise Linux Server Update Services for Sap Solutions](https://www.precursorintelligence.com/product/redhat/enterprise_linux_server_update_services_for_sap_solutions) by [Red Hat](https://www.precursorintelligence.com/vendors/redhat) (Application): 7.6, 7.7, 8.1, 8.2, 8.4
- [Ubuntu Linux](https://www.precursorintelligence.com/product/canonical/ubuntu_linux) by [Canonical](https://www.precursorintelligence.com/vendors/canonical) (Operating system): 14.04, 16.04, 18.04, 20.04, 21.10
- [Enterprise Linux Server Tus](https://www.precursorintelligence.com/product/redhat/enterprise_linux_server_tus) by [Red Hat](https://www.precursorintelligence.com/vendors/redhat) (Operating system): 7.6, 7.7, 8.2, 8.4
- [Enterprise Linux for Power Little Endian Eus](https://www.precursorintelligence.com/product/redhat/enterprise_linux_for_power_little_endian_eus) by [Red Hat](https://www.precursorintelligence.com/vendors/redhat) (Operating system): 8.1, 8.2, 8.4
- [Enterprise Linux for Ibm Z Systems](https://www.precursorintelligence.com/product/redhat/enterprise_linux_for_ibm_z_systems) by [Red Hat](https://www.precursorintelligence.com/vendors/redhat) (Operating system): 7.0, 8.0
- [Enterprise Linux for Ibm Z Systems Eus](https://www.precursorintelligence.com/product/redhat/enterprise_linux_for_ibm_z_systems_eus) by [Red Hat](https://www.precursorintelligence.com/vendors/redhat) (Operating system): 8.2, 8.4
- [Enterprise Linux for Power Little Endian](https://www.precursorintelligence.com/product/redhat/enterprise_linux_for_power_little_endian) by [Red Hat](https://www.precursorintelligence.com/vendors/redhat) (Operating system): 7.0, 8.0
- [Enterprise Linux Server](https://www.precursorintelligence.com/product/redhat/enterprise_linux_server) by [Red Hat](https://www.precursorintelligence.com/vendors/redhat) (Operating system): 6.0, 7.0
- [HTTP Server](https://www.precursorintelligence.com/product/oracle/http_server) by [Oracle](https://www.precursorintelligence.com/vendors/oracle) (Application): 12.2.1.3.0, 12.2.1.4.0
- [Command Center](https://www.precursorintelligence.com/product/starwindsoftware/command_center) by [Starwindsoftware](https://www.precursorintelligence.com/vendors/starwindsoftware) (Application): 1.0-update3_build5871
- [Enterprise Linux](https://www.precursorintelligence.com/product/redhat/enterprise_linux) by [Red Hat](https://www.precursorintelligence.com/vendors/redhat) (Operating system): 8.0
- [Enterprise Linux Desktop](https://www.precursorintelligence.com/product/redhat/enterprise_linux_desktop) by [Red Hat](https://www.precursorintelligence.com/vendors/redhat) (Operating system): 7.0
- [Enterprise Linux Eus](https://www.precursorintelligence.com/product/redhat/enterprise_linux_eus) by [Red Hat](https://www.precursorintelligence.com/vendors/redhat) (Operating system): 8.2
- [Enterprise Linux for Power Big Endian](https://www.precursorintelligence.com/product/redhat/enterprise_linux_for_power_big_endian) by [Red Hat](https://www.precursorintelligence.com/vendors/redhat) (Operating system): 7.0
- [Enterprise Linux for Scientific Computing](https://www.precursorintelligence.com/product/redhat/enterprise_linux_for_scientific_computing) by [Red Hat](https://www.precursorintelligence.com/vendors/redhat) (Operating system): 7.0
- [Enterprise Linux Server Eus](https://www.precursorintelligence.com/product/redhat/enterprise_linux_server_eus) by [Red Hat](https://www.precursorintelligence.com/vendors/redhat) (Operating system): 8.4
- [Enterprise Linux Workstation](https://www.precursorintelligence.com/product/redhat/enterprise_linux_workstation) by [Red Hat](https://www.precursorintelligence.com/vendors/redhat) (Operating system): 7.0
- [Enterprise Storage](https://www.precursorintelligence.com/product/suse/enterprise_storage) by [Suse](https://www.precursorintelligence.com/vendors/suse) (Application): 7.0
- [Linux Enterprise Desktop](https://www.precursorintelligence.com/product/suse/linux_enterprise_desktop) by [Suse](https://www.precursorintelligence.com/vendors/suse) (Operating system): 15-sp2
- [Linux Enterprise High Performance Computing](https://www.precursorintelligence.com/product/suse/linux_enterprise_high_performance_computing) by [Suse](https://www.precursorintelligence.com/vendors/suse) (Application): 15.0-sp2
- [Linux Enterprise Server](https://www.precursorintelligence.com/product/suse/linux_enterprise_server) by [Suse](https://www.precursorintelligence.com/vendors/suse) (Operating system): 15-sp2
- [Linux Enterprise Workstation Extension](https://www.precursorintelligence.com/product/suse/linux_enterprise_workstation_extension) by [Suse](https://www.precursorintelligence.com/vendors/suse) (Operating system): 12-sp5
- [Manager Proxy](https://www.precursorintelligence.com/product/suse/manager_proxy) by [Suse](https://www.precursorintelligence.com/vendors/suse) (Application): 4.1
- [Manager Server](https://www.precursorintelligence.com/product/suse/manager_server) by [Suse](https://www.precursorintelligence.com/vendors/suse) (Application): 4.1
- [Scalance Lpe9403 Firmware](https://www.precursorintelligence.com/product/siemens/scalance_lpe9403_firmware) by [Siemens](https://www.precursorintelligence.com/vendors/siemens) (Operating system): before 2.0
- [Sinumerik Edge](https://www.precursorintelligence.com/product/siemens/sinumerik_edge) by [Siemens](https://www.precursorintelligence.com/vendors/siemens) (Application): before 3.3.0
- [Starwind Virtual SAN](https://www.precursorintelligence.com/product/starwindsoftware/starwind_virtual_san) by [Starwindsoftware](https://www.precursorintelligence.com/vendors/starwindsoftware) (Application): v8-build14338
- [Zfs Storage Appliance Kit](https://www.precursorintelligence.com/product/oracle/zfs_storage_appliance_kit) by [Oracle](https://www.precursorintelligence.com/vendors/oracle) (Application): 8.8

## How do I fix CVE-2021-4034?

1. **Check whether you run it.** Compare your versions with the affected products above. Not sure what you run? Precursor Intelligence can work it out from your public website, or you can pick it from a list.
2. **Apply the vendor’s fix.** Install the update named in the vendor’s advisory. We’ve put the advisories and patch notes first in the list.
3. **If you can’t patch today.** Follow any mitigation the vendor publishes, and limit who can reach the affected system from the internet until the update is in.
4. **Check it wasn’t used before you patched.** Because criminals are already using this flaw, look for signs of a break-in on affected systems using the vendor’s guidance.

### References

- [bugzilla.redhat.com](https://bugzilla.redhat.com/show_bug.cgi?id=2025869) (Issue tracking, Patch)
- [gitlab.freedesktop.org](https://gitlab.freedesktop.org/polkit/polkit/-/commit/a2bf5c9c83b6ae46cbd5c779d3055bff81ded683) (Patch)
- [oracle.com](https://www.oracle.com/security-alerts/cpuapr2022.html) (Patch, Third-party advisory)
- [access.redhat.com](https://access.redhat.com/security/vulnerabilities/RHSB-2022-001) (Mitigation, Vendor advisory)
- [qualys.com](https://www.qualys.com/2022/01/25/cve-2021-4034/pwnkit.txt) (Exploit, Mitigation, Third-party advisory)
- [packetstormsecurity.com](http://packetstormsecurity.com/files/166196/Polkit-pkexec-Local-Privilege-Escalation.html) (Exploit, Third-party advisory, Vulnerability database)
- [packetstormsecurity.com](http://packetstormsecurity.com/files/166200/Polkit-pkexec-Privilege-Escalation.html) (Third-party advisory, Vulnerability database)
- [cert-portal.siemens.com](https://cert-portal.siemens.com/productcert/pdf/ssa-330556.pdf) (Third-party advisory)
- [secpod.com](https://www.secpod.com/blog/local-privilege-escalation-vulnerability-in-major-linux-distributions-cve-2021-4034/) (Exploit, Third-party advisory)
- [starwindsoftware.com](https://www.starwindsoftware.com/security/sw-20220818-0001/) (Third-party advisory)
- [suse.com](https://www.suse.com/support/kb/doc/?id=000020564) (Third-party advisory)
- [vicarius.io](https://www.vicarius.io/vsociety/posts/pwnkit-pkexec-lpe-cve-2021-4034) (Exploit, Third-party advisory)
- [cisa.gov](https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-4034) (Government resource)

## Questions

### What is CVE-2021-4034?

CVE-2021-4034 is a high-severity flaw in Polkit from Polkit Project, published on 28 January 2022. An attacker has to be already on the device with an ordinary user account, and nobody has to click anything. If it works, the attacker can read data, change data and take it offline.

### How serious is CVE-2021-4034?

It scores 7.8 out of 10 on the CVSS severity scale, which is high. Our risk score for CVE-2021-4034 is 80 out of 100, which is High. Its action is "Emergency patch". Attackers are using this flaw today. If you run an affected version, it goes to the top of your list.

### Is CVE-2021-4034 being exploited?

Attackers are already using it. It is on the government list of flaws known to be exploited, and the latest forecast puts the chance of it being used in the next 30 days at 95%.

### Which versions does CVE-2021-4034 affect?

For Polkit from Polkit Project: before 121. The record lists 30 products in all, each with its versions, under "Who is affected" on this page.

### How do I fix CVE-2021-4034?

Install the update the vendor names in its advisory, linked first under "How do I fix" on this page. If you can't patch today, follow the vendor's mitigation and limit who can reach the affected system from the internet. Because criminals are already using it, also check affected systems for signs of a break-in.

## Does CVE-2021-4034 affect you?

Precursor Intelligence keeps checking for you:

- **Tell us what you run.** Pick your software from a list, or let us work it out from your website.
- **We match it to every flaw.** Over 400,000 published flaws, checked against your list.
- **Ranked by real-world risk.** Every flaw gets a 0 to 100 risk score, kept up to date, led by evidence criminals are using it.
- **Told as soon as we know.** An alert by email, in the app or by webhook to your own tools.

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