---
id: "CVE-2021-34486"
kind: "vulnerability"
aliases: ["CVE-2021-34486"]
title: "Microsoft Windows: Microsoft Windows Event Tracing Privilege Escalation Vulnerability"
severity: "high"
cvss: 7.8
epss: 0.09253
exploited: true
status: "open"
category: "infrastructure"
products: [{"name": "Microsoft Windows", "fixed": [], "affected": "", "ecosystem": "vendor"}]
ecosystems: ["vendor"]
tags: ["exploited", "infrastructure", "self-hosted", "windows"]
not_affected_if: ["patched-windows-build"]
published_at: "2021-08-12T18:15:09+00:00"
first_seen_at: "2026-10-23T19:11:52+00:00"
updated_at: "2026-10-23T21:57:35+00:00"
sources: [{"source": "kev", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2021-34486", "first_seen_at": "2026-10-23T19:11:52+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2021-34486", "first_seen_at": "2026-10-23T19:13:44+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2021-34486", "first_seen_at": "2026-10-23T21:57:35+00:00"}]
---

# Microsoft Windows: Microsoft Windows Event Tracing Privilege Escalation Vulnerability

Microsoft Windows Event Tracing has a flaw that lets a local user escalate privileges on the machine. An attacker with a low-privilege foothold can gain SYSTEM-level control, and CISA lists it as actively exploited.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- vendor:Microsoft Windows affected ? fixed ?

## How to check

Check the installed Windows build against Microsoft's CVE-2021-34486 advisory (https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-34486) and confirm the August 2021 security update is installed.

## Fix

Install the Microsoft security update for CVE-2021-34486 from August 2021 or later via Windows Update.

## Timeline

- 2026-10-23T19:11:52+00:00 kev https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2021-34486
- 2026-10-23T19:13:44+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2021-34486
- 2026-10-23T21:57:35+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2021-34486

## From the sources

Microsoft Windows Event Tracing contains an unspecified vulnerability which can allow for privilege escalation.

CISA required action: Apply updates per vendor instructions.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_