Exploited CVEs / Red Hat / CVE-2021-4034
CVE-2021-4034
Red Hat Polkit Out-of-Bounds Read and Write Vulnerability. Exploitation in the wild is confirmed by CISA, not predicted. Federal agencies were required to remediate by 2022-07-18 (that deadline has passed); treat that date as the outer bound for your own environment. Check the vendor security advisory for the fix.
Risk summary
Actively exploited Red Hat Polkit vulnerability, High severity, CVSS 7.8. Added to the CISA KEV catalog 2022-06-27.
Senserva AI Opinion for CVE-2021-4034
The pkexec utility in Red Hat Polkit contains an out-of-bounds read and write giving local privilege escalation to root, CVSS 7.8 with a 95% EPSS score (KEV, 2022-06-27). What sets this apart is ubiquity: pkexec ships setuid-root on virtually every mainstream Linux distribution, so the exploit works almost anywhere an attacker gets a shell. It remains a standard post-exploitation step years later, which the near-maximal EPSS score confirms.
Do this: Patch polkit everywhere and, on systems that cannot update quickly, strip the setuid bit from pkexec as an interim mitigation.
AI-generated from public data, 2026-07-07. Verify against the vendor advisory before acting.
Senserva AI Opinion and rich prompt for CVE-2021-4034
Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.
Updated August 14, 2026. Data refreshed on every build from MSRC, CISA KEV, and FIRST EPSS.
Full tracking and change history for CVE-2021-4034
- Published
- 2022-06-27
- Last revised
- 2022-06-27
- Changes tracked
- 1
Published and last-revised dates are authoritative, from Microsoft MSRC (or the CISA KEV date-added). Senserva additionally records day-to-day changes from 2026-07-07, refreshed several times a day; the change count reflects that forward-only tracking.
- 2022-06-27 added to the CISA KEV catalog by CISA
- 2026-07-17 CVSS 0.0 to 7.8; EPSS first scored at 94.9%
Recorded by Senserva on the dates shown, from CISA KEV and FIRST EPSS. This is what moved and when, which neither the vendor advisory nor NVD publishes.
CISA required action
Federal (BOD 22-01) remediation due date: 2022-07-18 (past due).
Apply updates per vendor instructions.
Official fix for CVE-2021-4034
Check the vendor's security advisory channel for the patched Polkit versions and workarounds.
Common questions about CVE-2021-4034
Is CVE-2021-4034 actively exploited?
Yes. CVE-2021-4034 was added to the CISA Known Exploited Vulnerabilities (KEV) catalog on 2022-06-27, which means exploitation in the wild has been confirmed, not predicted. Its EPSS 30-day exploitation probability is 95%.
What is the CISA deadline and required action for CVE-2021-4034?
CISA set the federal (BOD 22-01) remediation due date at 2022-07-18, which has passed; treat any unremediated system as overdue. The verbatim required action: Apply updates per vendor instructions.
What fixes CVE-2021-4034?
Check the vendor's security advisory for the patched Polkit versions and any workarounds. KEV listing makes this a fix-first item: patch it ahead of higher-CVSS issues nobody is exploiting.
Can I ask my own AI about CVE-2021-4034?
Yes. This page includes a free, ready-to-paste AI prompt containing CVE-2021-4034's key facts: severity, CVSS, EPSS, the KEV date, the CISA due date, and the required action. Copy it into Claude, ChatGPT, or Copilot; the data is refreshed twice a day (5 AM and 3 PM US Central).
Scope and sources
- More exploited Red Hat CVEs
All Red Hat exploited CVEs on one page: Red Hat vulnerabilities actively exploited.
- Authoritative references
Every actively exploited CVE, searchable with due dates and CSV export: the exploited-CVE tracker. The newest additions: exploited this week.