# CVE-2021-4034: Red Hat Polkit Out-of-Bounds Read and Write Vulnerability

> CVE-2021-4034: Red Hat Polkit Out-of-Bounds Read and Write Vulnerability. CVSS 7.8 (CVSS 3.1), in CISA KEV.

Canonical: https://rewindex.com/cve/CVE-2021-4034
Last updated: 2026-08-15T03:55:29Z

- Published: 2022-01-28 00:00 UTC · Updated: 2026-08-15 03:55 UTC · Assigner: redhat
- CVSS: 7.8 (CVSS 3.1) · Severity: High · Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- EPSS: 94.9%, 100th percentile (scored 2026-10-25)
- CISA KEV: yes, added 2022-06-27, federal due date 2022-07-18, ransomware use: Known
- CWE: CWE-787

## 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.

## CISA required action

Apply updates per vendor instructions.

## Affected vendors and products

- n/a: polkit

## References

- [CVE record on cve.org](https://www.cve.org/CVERecord?id=CVE-2021-4034)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2021-4034)
- [http://packetstormsecurity.com/files/166196/Polkit-pkexec-Local-Privilege-Escalation.html](http://packetstormsecurity.com/files/166196/Polkit-pkexec-Local-Privilege-Escalation.html)
- [http://packetstormsecurity.com/files/166200/Polkit-pkexec-Privilege-Escalation.html](http://packetstormsecurity.com/files/166200/Polkit-pkexec-Privilege-Escalation.html)
- [https://access.redhat.com/security/vulnerabilities/RHSB-2022-001](https://access.redhat.com/security/vulnerabilities/RHSB-2022-001)
- [https://bugzilla.redhat.com/show\_bug.cgi?id=2025869](https://bugzilla.redhat.com/show_bug.cgi?id=2025869)
- [https://cert-portal.siemens.com/productcert/pdf/ssa-330556.pdf](https://cert-portal.siemens.com/productcert/pdf/ssa-330556.pdf)
- [https://gitlab.freedesktop.org/polkit/polkit/-/commit/a2bf5c9c83b6ae46cbd5c779d3055bff81ded683](https://gitlab.freedesktop.org/polkit/polkit/-/commit/a2bf5c9c83b6ae46cbd5c779d3055bff81ded683)
- [https://www.oracle.com/security-alerts/cpuapr2022.html](https://www.oracle.com/security-alerts/cpuapr2022.html)
- [https://www.qualys.com/2022/01/25/cve-2021-4034/pwnkit.txt](https://www.qualys.com/2022/01/25/cve-2021-4034/pwnkit.txt)
- [https://www.secpod.com/blog/local-privilege-escalation-vulnerability-in-major-linux-distributions-cve-2021-4034/](https://www.secpod.com/blog/local-privilege-escalation-vulnerability-in-major-linux-distributions-cve-2021-4034/)
- [https://www.starwindsoftware.com/security/sw-20220818-0001/](https://www.starwindsoftware.com/security/sw-20220818-0001/)
- [https://www.suse.com/support/kb/doc/?id=000020564](https://www.suse.com/support/kb/doc/?id=000020564)

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_Sources: CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (https://www.cve.org/) This product uses data from the NVD API but is not endorsed or certified by the NVD. (https://nvd.nist.gov/) Known Exploited Vulnerabilities catalog from CISA. (https://www.cisa.gov/known-exploited-vulnerabilities-catalog) EPSS scores from FIRST (Exploit Prediction Scoring System). (https://www.first.org/epss/)_


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Canonical: https://rewindex.com/cve/CVE-2021-4034 · Markdown: https://rewindex.com/cve/CVE-2021-4034.md · JSON: https://rewindex.com/api/v1/cves/CVE-2021-4034 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T03:09:44.925Z