IRONSMITHINTEL
HIGHCVSS7.8
|
Actively Exploited
|CISA KEV|CVE-2021-4034|Auth: low — authenticated user|Reboot: required|Manual only

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

The Red Hat polkit pkexec utility contains an out-of-bounds read and write vulnerability that allows for privilege escalation with administrative rights.

Published Jan 28, 2022 · Updated May 16, 2026
Why patchRisk explained in plain English
Worst-case scenarioIf unpatched

A local attacker, with a low-privilege account, can achieve full data confidentiality loss, arbitrary modification of data, complete denial of service or system unavailability. Federal agencies are required to remediate by 2022-07-18 under CISA BOD 22-01.

How the attack worksNo clicks needed

This is a Out-of-bounds Write (CWE-787) vulnerability in Red Hat Polkit. 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. Exploitation requires local access, low attack complexity, a low-privilege authenticated account, and no user interaction required.

Am I affected?Quick check

Probably yes if any of these apply:

IT Security
Running polkit: v < 121; enterprise linux server update services for sap solutions: 7.6, 7.7, 8.1, 8.2, 8.4; enterprise linux: 8.0; enterprise linux desktop: 7.0; enterprise linux eus: 8.2; enterprise linux for ibm z systems: 7.0, 8.0; enterprise linux for ibm z systems eus: 8.2, 8.4; enterprise linux for power big endian: 7.0; enterprise linux for power little endian: 7.0, 8.0; enterprise linux for power little endian eus: 8.1, 8.2, 8.4; enterprise linux for scientific computing: 7.0; enterprise linux server: 6.0, 7.0; enterprise linux server aus: 7.3, 7.4, 7.6, 7.7, 8.2, 8.4; enterprise linux server eus: 8.4; enterprise linux server tus: 7.6, 7.7, 8.2, 8.4; enterprise linux workstation: 7.0; ubuntu linux: 14.04, 16.04, 18.04, 20.04, 21.10; enterprise storage: 7.0; linux enterprise high performance computing: 15.0; manager proxy: 4.1; manager server: 4.1; linux enterprise desktop: 15; linux enterprise server: 15; linux enterprise workstation extension: 12; http server: 12.2.1.3.0, 12.2.1.4.0; zfs storage appliance kit: 8.8; sinumerik edge: v < 3.3.0; scalance lpe9403 firmware: v < 2.0; command center: 1.0; starwind virtual san: v8
Real-world incidentsWhat we've seen

Active exploitation documented in the wild. Threat-research write-up: http://packetstormsecurity.com/files/166196/Polkit-pkexec-Local-Privilege-Escalation.html

How to patch

Manual remediation steps

Apply the Vendor Patch

This vulnerability is in the CISA Known Exploited Vulnerabilities catalog — apply the vendor's security update as soon as possible.

CISA required action: Apply updates per vendor instructions.

References

    1
    Vendor advisory: https://access.redhat.com/security/vulnerabilities/RHSB-2022-001
    1
    NVD entry: https://nvd.nist.gov/vuln/detail/CVE-2021-4034
    1
    CISA KEV: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-4034
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