Out-of-Bounds Write in Red Hat Polkit (CVE-2021-4034, CVSS 7.8, KEV)

Summary

Out-of-bounds write in Red Hat Polkit (CVE-2021-4034). Successful exploitation can lead to full system takeover. Listed in CISA KEV — actively exploited.

Original description

The description as published by the source.

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.

Source: CISA Known Exploited Vulnerabilities NVD CISA KEV

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2021-4034 has been found in Red Hat Polkit.
Successful exploitation can lead to full system takeover. CVSS score: 7.8/10.
Note: CISA has officially confirmed this is actively exploited in the wild. Treat it with elevated urgency.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Red Hat Polkit CVE-2021-4034" on the vendor's site.

CVE-2021-4034 (Red Hat Polkit) — CWE-787 / CVSS v3 7.8
Attack vector: local / no user interaction
Listed in CISA KEV — actively exploited, treat as top priority.
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

Out-of-bounds write (CWE-787) exists in Red Hat Polkit.

📍 Affected scope

Check the vendor advisory for the affected versions of Red Hat Polkit.

🔥 Severity

Severity: High (CVSS 7.8/10). Successful exploitation can lead to full system takeover. Listed in CISA KEV — actively exploited in the wild, treat as top priority.

🔧 How to fix

Update to the patched release per vendor advisory.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Audit SBOM/dependencies to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

1
Identify exposure identify
```
Audit SBOM/dependencies for affected components.
```
資産台帳・SBOM・依存マニフェストで Red Hat Polkit を使っているサービスとバージョンを洗い出す。
2
Consider incident declaration escalate
```
Notify SOC / on-call
```
CISA KEV登録済 = 実環境で悪用が観測されている。侵入の兆候があればインシデント対応宣言、無くてもパッチ適用までWAF強化を最優先で。
3
Post-deployment verification verify
```
Confirm patched version is live in production
```
パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Fix status by distribution

Fixed packages published by each distribution for this CVE

Debian DEBIAN-CVE-2021-4034 policykit-1 Fixed in: 0.105-31.1

[KEV] Out-of-Bounds Write in Red Hat Polkit (CVE-2021-4034)

Summary

Original description

Auto-generated summary

Response actions

Fix status by distribution

References