# CVE-2017-8691: Express Compressed Fonts Remote Code Execution Vulnerability

CVE-2017-8691 is fixed in 10 products on 1 platform, first by KB4034679, released August 8, 2017. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2017-8691
- Priority: Routine
- CVSS: 5.0 (Important)
- EPSS: 0.1977
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Vendor exploitability assessment: Exploitation Less Likely
- Published: Aug 8, 2017
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2017-8691

## Description

<p>A remote code execution vulnerability exists when the Windows font library improperly handles specially crafted embedded fonts. An attacker who successfully exploits exploited this vulnerability would gain code execution on the target system. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.</p> <p>There are multiple ways an attacker could exploit the vulnerability:</p> <ul> <li>In a web-based attack scenario, an attacker could host a specially crafted website that is designed to exploit the vulnerability and then convince users to view the website. An attacker would have no way to force users to view the attacker-controlled content. Instead, an attacker would have to convince users to take action, typically by getting them to click a link in an email or Instant Messenger message that takes users to the attacker's website, or by opening an attachment sent through email.</li> <li>In a file sharing attack scenario, an attacker could provide a specially crafted document file that is designed to exploit the vulnerability, and then convince users to open the document file.</li> </ul> <p>The security update addresses the vulnerability by correcting how the Windows font library handles embedded fonts.</p>

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Microsoft | Windows 7 for 32-bit Systems Service Pack 1 |  | [KB4034679](https://patchblox.com/security/data/fix/microsoft/kb4034679.md) | Aug 8, 2017 |
| Microsoft | Windows 7 for 32-bit Systems Service Pack 1 |  | [KB4034664](https://patchblox.com/security/data/fix/microsoft/kb4034664.md) | Aug 8, 2017 |
| Microsoft | Windows 7 for x64-based Systems Service Pack 1 |  | [KB4034679](https://patchblox.com/security/data/fix/microsoft/kb4034679.md) | Aug 8, 2017 |
| Microsoft | Windows 7 for x64-based Systems Service Pack 1 |  | [KB4034664](https://patchblox.com/security/data/fix/microsoft/kb4034664.md) | Aug 8, 2017 |
| Microsoft | Windows Server 2008 R2 for Itanium-Based Systems Service Pack 1 |  | [KB4034679](https://patchblox.com/security/data/fix/microsoft/kb4034679.md) | Aug 8, 2017 |
| Microsoft | Windows Server 2008 R2 for Itanium-Based Systems Service Pack 1 |  | [KB4034664](https://patchblox.com/security/data/fix/microsoft/kb4034664.md) | Aug 8, 2017 |
| Microsoft | Windows Server 2008 R2 for x64-based Systems Service Pack 1 |  | [KB4034679](https://patchblox.com/security/data/fix/microsoft/kb4034679.md) | Aug 8, 2017 |
| Microsoft | Windows Server 2008 R2 for x64-based Systems Service Pack 1 |  | [KB4034664](https://patchblox.com/security/data/fix/microsoft/kb4034664.md) | Aug 8, 2017 |
| Microsoft | Windows Server 2008 R2 for x64-based Systems Service Pack 1 (Server Core installation) |  | [KB4034679](https://patchblox.com/security/data/fix/microsoft/kb4034679.md) | Aug 8, 2017 |
| Microsoft | Windows Server 2008 R2 for x64-based Systems Service Pack 1 (Server Core installation) |  | [KB4034664](https://patchblox.com/security/data/fix/microsoft/kb4034664.md) | Aug 8, 2017 |
| Microsoft | Windows Server 2008 for 32-bit Systems Service Pack 2 |  | [KB4035056](https://patchblox.com/security/data/fix/microsoft/kb4035056.md) | Aug 8, 2017 |
| Microsoft | Windows Server 2008 for 32-bit Systems Service Pack 2 (Server Core installation) |  | [KB4035056](https://patchblox.com/security/data/fix/microsoft/kb4035056.md) | Aug 8, 2017 |
| Microsoft | Windows Server 2008 for Itanium-Based Systems Service Pack 2 |  | [KB4035056](https://patchblox.com/security/data/fix/microsoft/kb4035056.md) | Aug 8, 2017 |
| Microsoft | Windows Server 2008 for x64-based Systems Service Pack 2 |  | [KB4035056](https://patchblox.com/security/data/fix/microsoft/kb4035056.md) | Aug 8, 2017 |
| Microsoft | Windows Server 2008 for x64-based Systems Service Pack 2 (Server Core installation) |  | [KB4035056](https://patchblox.com/security/data/fix/microsoft/kb4035056.md) | Aug 8, 2017 |

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Data as of 2026-11-07T12:40:37Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo