CVE-2014-2240 in FreeType
Summary
by MITRE
Stack-based buffer overflow in the cf2_hintmap_build function in cff/cf2hints.c in FreeType before 2.5.3 allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via a large number of stem hints in a font file.
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Analysis
by VulDB Data Team • 05/07/2026
The vulnerability identified as CVE-2014-2240 represents a critical stack-based buffer overflow within the FreeType font rendering library, specifically affecting the cf2_hintmap_build function in the cff/cf2hints.c source file. This flaw exists in FreeType versions prior to 2.5.3 and demonstrates a classic software security weakness that can be exploited remotely to compromise system integrity. The vulnerability stems from inadequate input validation when processing font files, particularly those containing an excessive number of stem hints that exceed the allocated stack buffer space. According to CWE-121, this corresponds to a stack-based buffer overflow condition where the program fails to properly check the size of data being copied to a stack buffer, creating a potential exploitation vector for malicious actors. The affected FreeType library serves as a fundamental component in numerous operating systems, applications, and web browsers that rely on proper font rendering capabilities, making this vulnerability particularly dangerous in widespread deployment scenarios.
The technical implementation of this vulnerability occurs during the processing of OpenType and TrueType font files where the cf2_hintmap_build function attempts to construct hint maps for font rendering operations. When a font file contains an excessive number of stem hints, the function fails to validate the input parameters against predetermined buffer limits, leading to memory corruption on the stack. This condition allows attackers to overwrite adjacent stack memory locations, potentially corrupting return addresses and control flow information. The flaw operates through a predictable pattern where the number of stem hints directly correlates to the buffer overflow severity, enabling attackers to craft malicious font files that trigger the vulnerability. The vulnerability aligns with ATT&CK technique T1059.007 for execution through the manipulation of font rendering processes, and represents a classic example of how font processing libraries can become attack surfaces for privilege escalation and code execution exploits.
The operational impact of CVE-2014-2240 extends beyond simple denial of service conditions to potentially enable arbitrary code execution in vulnerable systems. When exploited successfully, this vulnerability can cause applications using FreeType to crash or terminate unexpectedly, resulting in service disruption and potential system instability. However, the more severe implications involve the possibility of attackers leveraging the buffer overflow to execute malicious code within the context of the affected application, potentially leading to complete system compromise. The vulnerability affects a wide range of applications that utilize FreeType for font rendering including web browsers, office suites, graphic design software, and operating system components. The remote exploitation capability means that attackers can deliver malicious font files through various vectors such as web pages, email attachments, or file sharing platforms without requiring local system access. This makes the vulnerability particularly concerning for enterprise environments where users may encounter untrusted font content through normal browsing or document processing activities.
Mitigation strategies for CVE-2014-2240 primarily focus on updating to FreeType version 2.5.3 or later, which includes patches that properly validate input parameters and implement appropriate buffer size checks. System administrators should prioritize patching all affected applications and operating systems that rely on FreeType for font rendering operations. Additional defensive measures include implementing strict font file validation policies, particularly for untrusted content, and deploying network-based intrusion detection systems that can identify suspicious font file patterns. Organizations should also consider implementing application whitelisting controls that restrict font processing to known good applications and files. The vulnerability serves as a reminder of the importance of proper input validation in font processing libraries and highlights the need for regular security assessments of core system components. Security monitoring should include detection of unusual font file processing activities and memory corruption patterns that may indicate exploitation attempts. Given the widespread use of FreeType across multiple platforms and applications, comprehensive vulnerability management programs must include regular auditing of font rendering libraries and their associated security patches to prevent successful exploitation of similar buffer overflow conditions.