CVE-2021-4034
Red Hat Polkit Out-of-Bounds Read and Write Vulnerability
Does this matter?
Known to be exploited in the wild (CISA KEV, CISA remediation deadline 18 July 2022). Treat as an emergency change: patch or isolate now, then hunt for prior compromise.
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.
- CVSS 3.1
- 7.8 HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 94.92% probability · 100th percentile
- Public exploits
- 1 in Exploit-DB · first 27 January 2022
- CISA KEV
- Listed 27 June 2022 · due 18 July 2022 · used in ransomware campaigns
- Weakness
- CWE-787, CWE-125
- Affected
- polkit project/polkit · redhat/enterprise linux server update services for sap solutions · redhat/enterprise linux · redhat/enterprise linux desktop · redhat/enterprise linux eus · redhat/enterprise linux for ibm z systems · redhat/enterprise linux for ibm z systems eus · redhat/enterprise linux for power big endian · redhat/enterprise linux for power little endian · redhat/enterprise linux for power little endian eus · redhat/enterprise linux for scientific computing · redhat/enterprise linux server · redhat/enterprise linux server aus · redhat/enterprise linux server eus · redhat/enterprise linux server tus · redhat/enterprise linux workstation · canonical/ubuntu linux · suse/enterprise storage · suse/linux enterprise high performance computing · suse/manager proxy · +10 more
- Source
- secalert@redhat.com
EPSS 94.9% since 30 October 2026; no change recorded yet. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
CISA notes
Apply updates per vendor instructions. https://nvd.nist.gov/vuln/detail/CVE-2021-4034
Public exploits (1)
Entries in Exploit-DB that cite this CVE. Links go to the Exploit-DB page and to the file in the public repository; nothing is hosted here. A verified tick means the Exploit-DB team confirmed the exploit works against the stated version.
References
- http://packetstormsecurity.com/files/166196/Polkit-pkexec-Local-Privilege-Escalation.htmlExploit, Third Party Advisory, VDB Entry
- http://packetstormsecurity.com/files/166200/Polkit-pkexec-Privilege-Escalation.htmlThird Party Advisory, VDB Entry
- https://access.redhat.com/security/vulnerabilities/RHSB-2022-001Mitigation, Vendor Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=2025869Issue Tracking, Patch
- https://cert-portal.siemens.com/productcert/pdf/ssa-330556.pdfThird Party Advisory
- https://gitlab.freedesktop.org/polkit/polkit/-/commit/a2bf5c9c83b6ae46cbd5c779d3055bff81ded683Patch
- https://www.oracle.com/security-alerts/cpuapr2022.htmlPatch, Third Party Advisory
- https://www.qualys.com/2022/01/25/cve-2021-4034/pwnkit.txtExploit, Mitigation, Third Party Advisory
- https://www.secpod.com/blog/local-privilege-escalation-vulnerability-in-major-linux-distributions-cve-2021-4034/Exploit, Third Party Advisory
- https://www.starwindsoftware.com/security/sw-20220818-0001/Third Party Advisory
- https://www.suse.com/support/kb/doc/?id=000020564Third Party Advisory
- http://packetstormsecurity.com/files/166196/Polkit-pkexec-Local-Privilege-Escalation.htmlExploit, Third Party Advisory, VDB Entry
- http://packetstormsecurity.com/files/166200/Polkit-pkexec-Privilege-Escalation.htmlThird Party Advisory, VDB Entry
- https://access.redhat.com/security/vulnerabilities/RHSB-2022-001Mitigation, Vendor Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=2025869Issue Tracking, Patch
- https://cert-portal.siemens.com/productcert/pdf/ssa-330556.pdfThird Party Advisory
- https://gitlab.freedesktop.org/polkit/polkit/-/commit/a2bf5c9c83b6ae46cbd5c779d3055bff81ded683Patch
- https://www.oracle.com/security-alerts/cpuapr2022.htmlPatch, Third Party Advisory
- https://www.qualys.com/2022/01/25/cve-2021-4034/pwnkit.txtExploit, Mitigation, Third Party Advisory
- https://www.secpod.com/blog/local-privilege-escalation-vulnerability-in-major-linux-distributions-cve-2021-4034/Exploit, Third Party Advisory
- https://www.starwindsoftware.com/security/sw-20220818-0001/Third Party Advisory
- https://www.suse.com/support/kb/doc/?id=000020564Third Party Advisory
- https://www.vicarius.io/vsociety/posts/pwnkit-pkexec-lpe-cve-2021-4034Exploit, Third Party Advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-4034US Government Resource
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.