CVE-2015-2426 in Windows
Summary
by MITRE
Buffer underflow in atmfd.dll in the Windows Adobe Type Manager Library in Microsoft Windows Vista SP2, Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1, Windows 8, Windows 8.1, Windows Server 2012 Gold and R2, and Windows RT Gold and 8.1 allows remote attackers to execute arbitrary code via a crafted OpenType font, aka "OpenType Font Driver Vulnerability."
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 04/22/2026
The vulnerability identified as CVE-2015-2426 represents a critical buffer underflow condition within the atmfd.dll component of Microsoft Windows operating systems. This flaw exists within the Windows Adobe Type Manager Library, which serves as the core font handling mechanism for rendering OpenType fonts across the affected Windows versions including Vista SP2 through Windows 8.1 and their respective server editions. The vulnerability specifically manifests when the system processes maliciously crafted OpenType font files, creating a scenario where attacker-controlled data can overwrite adjacent memory locations in the application's memory space.
The technical nature of this vulnerability stems from improper bounds checking within the font parsing routine of atmfd.dll. When the system attempts to process a specially constructed OpenType font file, the parsing logic fails to adequately validate the size and structure of font data elements, particularly within the font table structures. This inadequate validation allows an attacker to craft font files that contain malformed data sequences which, when processed by the vulnerable library, cause the program to write data beyond the allocated buffer boundaries. The underlying weakness aligns with CWE-121, which describes stack-based buffer overflow conditions, though this specific case involves a buffer underflow scenario where insufficient data is written to trigger memory corruption.
The operational impact of this vulnerability extends far beyond simple denial of service conditions, as it provides remote attackers with the capability to execute arbitrary code with the privileges of the affected application. Since the Windows Adobe Type Manager Library is invoked during normal font rendering operations, attackers can trigger this vulnerability through various attack vectors including email attachments, web downloads, or network shares containing malicious font files. The exploitation process typically involves crafting a font file that, when opened or rendered by the Windows system, causes the buffer underflow to corrupt critical memory regions including return addresses or function pointers. This memory corruption enables attackers to redirect program execution flow and inject malicious code, potentially leading to full system compromise according to ATT&CK technique T1059.007 for command and scripting interpreter.
The affected systems represent a broad range of Microsoft Windows operating systems that were prevalent during the period when this vulnerability existed, making the potential attack surface particularly extensive. Organizations running these vulnerable versions face significant risk as the vulnerability can be exploited through legitimate font rendering pathways that are commonly encountered in office environments, web browsing scenarios, and document processing workflows. The vulnerability's remote exploitation capability means that attackers do not require physical access to target systems or local network presence to deliver payloads, making it particularly dangerous in enterprise environments where users regularly interact with untrusted font content from various sources.
Mitigation strategies for this vulnerability primarily focus on immediate patching and system hardening measures. Microsoft released security updates through Windows Update and Windows Server Update Services that corrected the buffer underflow condition in the affected Adobe Type Manager components. Organizations should prioritize deployment of these patches across all affected systems, particularly those that process untrusted font content or operate in high-risk environments. Additional protective measures include implementing application whitelisting policies to restrict font processing applications, disabling automatic font rendering in web browsers and email clients, and employing network-based intrusion detection systems to monitor for potential exploitation attempts. The vulnerability demonstrates the critical importance of font security in operating system design and highlights the necessity for robust input validation and memory safety mechanisms in font rendering libraries. Security professionals should also consider implementing monitoring for unusual font processing activity and establishing incident response procedures specifically addressing font-based exploitation attempts.