CVE-2021-4034
CISA KEVAs of 2025-11-06, CVE-2021-4034 is a CVSS 7.8 (HIGH-severity) vulnerability. CISA KEV-listed (known exploited). EPSS exploitation probability 87.8%. Threadlinqs Intelligence tracks 3 threats exploiting it.
Last updated: 2025-11-06
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 v3 vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Weaknesses (CWE)
CWE-787, CWE-125
Exploitation status
CISA KEV-listed (known exploited)
Threats tracking this CVE
- PCPJack Covert SMTP Relay Network — 230 Hijacked AWS/Google Cloud/Azure Servers via Sliver C2 + Chisel SOCKS Tunneling — HIGH
- SHADOW-AETHER-040 & SHADOW-AETHER-064 — Agentic AI-Driven Intrusion Campaigns Targeting LATAM Government and Financial Sectors (Vibe Hacking) — CRITICAL
- CL-UNK-1068: China-Nexus APT Targeting Critical Infrastructure via DLL Sideloading, Xnote Backdoor, ScanPortPlus Scanner, and FRP Tunneling — HIGH
References
- http://packetstormsecurity.com/files/166196/Polkit-pkexec-Local-Privilege-Escalation.html
- http://packetstormsecurity.com/files/166200/Polkit-pkexec-Privilege-Escalation.html
- https://access.redhat.com/security/vulnerabilities/RHSB-2022-001
- https://bugzilla.redhat.com/show_bug.cgi?id=2025869
- https://cert-portal.siemens.com/productcert/pdf/ssa-330556.pdf
- https://gitlab.freedesktop.org/polkit/polkit/-/commit/a2bf5c9c83b6ae46cbd5c779d3055bff81ded683
- https://www.oracle.com/security-alerts/cpuapr2022.html
- 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.starwindsoftware.com/security/sw-20220818-0001/
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Enriched from CVE.org, NVD (this product uses the NVD API but is not endorsed or certified by the NVD), FIRST EPSS, CISA KEV, and GitHub Security Advisories.