CVE-2016-3303 in Windows
Summary
by MITRE
The Windows font library in Microsoft Windows Vista SP2, Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1, Office 2007 SP3, Office 2010 SP2, Word Viewer, Skype for Business 2016, Lync 2013 SP1, Lync 2010, Lync 2010 Attendee, and Live Meeting 2007 Console allows remote attackers to execute arbitrary code via a crafted embedded font, aka "Windows Graphics Component RCE Vulnerability," a different vulnerability than CVE-2016-3304.
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Analysis
by VulDB Data Team • 03/14/2025
The vulnerability identified as CVE-2016-3303 represents a critical remote code execution flaw within the Windows font handling subsystem that affects multiple Microsoft operating systems and applications. This vulnerability specifically resides in the Windows font library component that processes embedded fonts, creating a pathway for malicious actors to execute arbitrary code on affected systems. The flaw manifests when the system processes specially crafted font files that contain malformed data structures, allowing attackers to leverage memory corruption techniques to gain unauthorized system access.
The technical exploitation of this vulnerability occurs through the manipulation of font parsing routines within the Windows graphics component, which operates under the Common Weakness Enumeration classification of CWE-125: "Out-of-bounds Read." The vulnerability stems from insufficient bounds checking during font file processing, particularly when handling embedded font data within compound document formats or when rendering fonts in graphical user interfaces. Attackers can craft malicious font files that trigger buffer overflows or heap corruption when the vulnerable components attempt to parse and render these malformed structures, ultimately leading to code execution at the privilege level of the affected application.
From an operational perspective, this vulnerability presents significant risk to enterprise environments as it can be exploited through multiple attack vectors including email attachments, web downloads, and document sharing scenarios. The impact extends across numerous Microsoft products and operating systems, making it particularly dangerous as it affects both desktop and server environments. The vulnerability's exploitation requires minimal user interaction, often succeeding through automatic font rendering when documents are opened or when web pages display embedded fonts. Security researchers have documented that this vulnerability can be leveraged to bypass modern security mitigations including address space layout randomization and data execution prevention mechanisms.
Organizations affected by this vulnerability should implement immediate mitigations including applying the relevant security patches released by Microsoft as part of their regular update cycle. The vulnerability's presence in Office applications makes it particularly concerning for enterprise users who frequently handle documents from external sources. Network segmentation and email filtering measures should be enhanced to prevent the delivery of potentially malicious font files. Additionally, system administrators should consider disabling automatic font rendering in web browsers and email clients where possible. The vulnerability aligns with ATT&CK technique T1203: "Exploitation for Client Execution" and demonstrates the importance of maintaining up-to-date security patches across all system components to prevent exploitation of known vulnerabilities in commonly used software libraries.