CVE-2011-3402: Microsoft Windows remote code execution in TrueType font parsing engine

CVE-2011-3402 · Severity: critical · CVSS 8.8 · Exploited in the wild · Published 2025-10-06

A vulnerability exists in how older versions of Microsoft Windows process TrueType fonts. An attacker can exploit this by tricking a user into opening a malicious Word document or visiting a compromised website, potentially allowing the attacker to take full control of the computer. This flaw was notably used in the wild by the Duqu malware to target industrial and government systems.

Technologies: Microsoft Windows. Vendors: Microsoft.

Quick answers

Is CVE-2011-3402 exploited in the wild?
Yes. CVE-2011-3402 is known to be exploited in the wild, first recorded on 6 October 2025. Treat it as urgent.
How severe is CVE-2011-3402?
Critical severity, with a CVSS score of 8.8, published 6 October 2025.
Which products and versions are affected?
Microsoft Windows XP SP2, SP3; Microsoft Windows Server 2003 SP2; Microsoft Windows Vista SP2; Microsoft Windows Server 2008 SP2, R2, R2 SP1; and 1 more.
Is there a fix for CVE-2011-3402?
No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2011-3402 attacked?
It is attacked over the network, in an operating system.
Am I affected by CVE-2011-3402?
Check whether you run Microsoft Windows. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

The vulnerability resides within the TrueType font parsing engine in the kernel-mode driver win32k.sys. It is triggered when the system processes specially crafted font data embedded in documents (such as Microsoft Word) or delivered via web pages. Because the parsing occurs in kernel mode, successful exploitation allows an attacker to execute arbitrary code with elevated privileges. This is a remote attack vector that requires user interaction (opening a file or visiting a site). Microsoft has released security bulletins (MS11-087, MS12-034) to address this issue.

Affected products

  • Microsoft Windows XP SP2, SP3
  • Microsoft Windows Server 2003 SP2
  • Microsoft Windows Vista SP2
  • Microsoft Windows Server 2008 SP2, R2, R2 SP1
  • Microsoft Windows 7 Gold, SP1

Timeline

  • 2011-11-03: disclosed: Initial Microsoft security advisory released
  • 2011-11-01: exploited: Exploited in the wild by Duqu malware
  • 2025-10-06: kev added: Added to CISA Known Exploited Vulnerabilities catalog

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