polkit /usr/bin/pkexec access control

CVSS Meta Temp Score
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CTI Interest Score
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8.0$0-$5k0.00

Summaryinfo

A vulnerability classified as critical has been found in polkit. Impacted is an unknown function of the file /usr/bin/pkexec. The manipulation leads to access control. This vulnerability is listed as CVE-2021-4034. The attack may be initiated remotely. In addition, an exploit is available. You should change the configuration settings.

Detailsinfo

A vulnerability, which was classified as critical, has been found in polkit (version now known). This issue affects some unknown processing of the file /usr/bin/pkexec. The manipulation with an unknown input leads to a access control vulnerability. Using CWE to declare the problem leads to CWE-284. The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

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.

The weakness was presented 01/26/2022. It is possible to read the advisory at qualys.com. The identification of this vulnerability is CVE-2021-4034 since 11/29/2021. Technical details as well as a public exploit are known. The attack technique deployed by this issue is T1068 according to MITRE ATT&CK.

A public exploit has been developed by BLASTY in C and been published even before and not after the advisory. The exploit is available at haxx.in. It is declared as attacked. The vulnerability was handled as a non-public zero-day exploit for at least 1 days. During that time the estimated underground price was around $0-$5k. The vulnerability scanner Nessus provides a plugin with the ID 236558 (Alibaba Cloud Linux 3 : 0004: polkit (ALINUX3-SA-2022:0004)), which helps to determine the existence of the flaw in a target environment. The CISA Known Exploited Vulnerabilities Catalog lists this issue since 06/27/2022 with a due date of 07/18/2022:

Apply updates per vendor instructions.

It is possible to mitigate the problem by applying the configuration setting chmod 0755 /usr/bin/pkexec.

The vulnerability is also documented in the databases at Exploit-DB (50689) and Tenable (236558). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Name

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 8.1
VulDB Meta Temp Score: 8.0

VulDB Base Score: 8.8
VulDB Temp Score: 8.6
VulDB Vector: 🔍
VulDB Reliability: 🔍

NVD Base Score: 7.8
NVD Vector: 🔍

CNA Base Score: 7.8
CNA Vector: 🔍

ADP CISA Base Score: 7.8
ADP CISA Vector: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

NVD Base Score: 🔍

Exploitinginfo

Class: Access control
CWE: CWE-284 / CWE-266
CAPEC: 🔍
ATT&CK: 🔍

Physical: Partially
Local: Yes
Remote: Yes

Availability: 🔍
Access: Public
Status: Attacked
Author: BLASTY
Programming Language: 🔍
Download: 🔍

EPSS Score: 🔍
EPSS Percentile: 🔍

KEV Added: 🔍
KEV Due: 🔍
KEV Remediation: 🔍
KEV Ransomware: 🔍
KEV Notice: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

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Nessus ID: 236558
Nessus Name: Alibaba Cloud Linux 3 : 0004: polkit (ALINUX3-SA-2022:0004)

Exploit-DB: 🔍

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Config
Status: 🔍

0-Day Time: 🔍

Config: chmod 0755 /usr/bin/pkexec

Timelineinfo

11/29/2021 🔍
01/25/2022 +57 days 🔍
01/26/2022 +1 days 🔍
01/26/2022 +0 days 🔍
08/15/2026 +1662 days 🔍

Sourcesinfo

Advisory: qualys.com
Status: Confirmed

CVE: CVE-2021-4034 (🔍)
GCVE (CVE): GCVE-0-2021-4034
GCVE (VulDB): GCVE-100-191603
scip Labs: https://www.scip.ch/en/?labs.20161013

Entryinfo

Created: 01/26/2022 07:20
Updated: 08/15/2026 06:53
Changes: 01/26/2022 07:20 (39), 01/26/2022 07:25 (1), 01/26/2022 07:58 (6), 04/27/2024 09:23 (28), 06/28/2024 22:58 (20), 09/18/2024 21:53 (1), 09/22/2024 23:32 (1), 11/04/2024 18:05 (10), 05/21/2025 21:20 (2), 08/14/2026 23:00 (2), 08/15/2026 06:53 (10)
Complete: 🔍
Submitter: misc
Committer: misc
Cache ID: 216::103

Submitinfo

Accepted

  • Submit #29334: Local Privilege Escalation in polkit's pkexec (by misc)

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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