---
id: "CVE-2011-3402"
kind: "vulnerability"
aliases: ["CVE-2011-3402"]
title: "Unspecified vulnerability in the TrueType font parsing engine in win32k.sys in the kernel-mode drivers in Microsoft\u2026"
severity: "critical"
cvss: 9.3
epss: null
exploited: true
status: "open"
category: "infrastructure"
products: [{"name": "Microsoft Windows", "fixed": [], "affected": "", "ecosystem": "vendor"}, {"name": "microsoft windows 7", "fixed": [], "affected": "", "ecosystem": "vendor"}, {"name": "microsoft windows server 2003", "fixed": [], "affected": "", "ecosystem": "vendor"}, {"name": "microsoft windows server 2008", "fixed": [], "affected": "", "ecosystem": "vendor"}, {"name": "microsoft windows vista", "fixed": [], "affected": "", "ecosystem": "vendor"}, {"name": "microsoft windows xp", "fixed": [], "affected": "", "ecosystem": "vendor"}]
ecosystems: ["vendor"]
tags: ["exploited", "infrastructure", "internet-explorer", "microsoft-office", "windows"]
not_affected_if: ["patched-windows"]
published_at: "2011-11-04T21:55:04+00:00"
first_seen_at: "2026-10-23T19:11:51+00:00"
updated_at: "2026-10-23T23:44:51+00:00"
sources: [{"source": "kev", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2011-3402", "first_seen_at": "2026-10-23T19:11:51+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2011-3402", "first_seen_at": "2026-10-23T23:44:51+00:00"}]
---

# Unspecified vulnerability in the TrueType font parsing engine in win32k.sys in the kernel-mode drivers in Microsoft…

A flaw in the TrueType font parser inside the Windows kernel driver win32k.sys lets crafted font data run code. An attacker gets code execution on the machine when a user opens a crafted Word document or visits a crafted web page.

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

## Affected

- vendor:Microsoft Windows affected ? fixed ?
- vendor:microsoft windows 7 affected ? fixed ?
- vendor:microsoft windows server 2003 affected ? fixed ?
- vendor:microsoft windows server 2008 affected ? fixed ?
- vendor:microsoft windows vista affected ? fixed ?
- vendor:microsoft windows xp affected ? fixed ?

## Fix

Apply the Microsoft security update for CVE-2011-3402 (MS11-087); the sources do not give a KB number, so confirm it against Microsoft's bulletin.
Follow CISA's KEV guidance: apply vendor mitigations or discontinue use of the product if mitigations are unavailable.

## Timeline

- 2026-10-23T19:11:51+00:00 kev https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2011-3402
- 2026-10-23T23:44:51+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2011-3402

## From the sources

Unspecified vulnerability in the TrueType font parsing engine in win32k.sys in the kernel-mode drivers in Microsoft Windows XP SP2 and SP3, Windows Server 2003 SP2, Windows Vista SP2, Windows Server 2008 SP2, R2, and R2 SP1, and Windows 7 Gold and SP1 allows remote attackers to execute arbitrary code via crafted font data in a Word document or web page, as exploited in the wild in November 2011 by Duqu, aka "TrueType Font Parsing Vulnerability."

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