CVE-2010-2806 in FreeType
Summary
by MITRE
Array index error in the t42_parse_sfnts function in type42/t42parse.c in FreeType before 2.4.2 allows remote attackers to cause a denial of service (application crash) or possibly execute arbitrary code via negative size values for certain strings in FontType42 font files, leading to a heap-based buffer overflow.
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Analysis
by VulDB Data Team • 09/23/2021
The vulnerability described in CVE-2010-2806 represents a critical heap-based buffer overflow flaw within the FreeType font rendering library, specifically affecting versions prior to 2.4.2. This issue resides in the t42_parse_sfnts function located in the type42/t42parse.c source file, which handles the parsing of FontType42 font files. The flaw manifests when the function processes certain strings within these font files that contain negative size values, creating a condition where array indexing operations become unpredictable and potentially dangerous. The vulnerability operates through a fundamental error in input validation and bounds checking, where the library fails to properly validate the size parameters of font data structures before attempting to allocate or access memory regions.
The technical exploitation of this vulnerability occurs when a maliciously crafted FontType42 font file is processed by an application using the affected FreeType library. When the t42_parse_sfnts function encounters negative size values in string data structures, it attempts to use these invalid values as array indices or buffer sizes, leading to heap memory corruption. This improper handling of size parameters creates a situation where the application may attempt to write data beyond the allocated buffer boundaries, resulting in memory corruption that can manifest as application crashes or, in more sophisticated exploitation scenarios, arbitrary code execution. The vulnerability demonstrates characteristics consistent with CWE-129 Input Validation and CWE-787 Out-of-bounds Write, where insufficient validation of input data leads to memory corruption.
The operational impact of this vulnerability extends beyond simple denial of service to potentially enable remote code execution, making it particularly dangerous for applications that process untrusted font data. Systems utilizing FreeType for font rendering across web browsers, desktop applications, or any software that handles font files become vulnerable when using affected library versions. The attack surface includes any application that processes FontType42 fonts, which are commonly found in PostScript-based font formats and are widely used in various operating systems and applications. This vulnerability can be exploited through multiple attack vectors including web browsers processing embedded fonts, email clients handling font-based attachments, or any software that dynamically loads and renders font files from untrusted sources. The potential for remote code execution through heap corruption makes this a high-severity vulnerability that requires immediate remediation.
Mitigation strategies for CVE-2010-2806 primarily focus on upgrading to FreeType version 2.4.2 or later, where the vulnerability has been addressed through proper input validation and bounds checking mechanisms. System administrators should implement comprehensive patch management processes to ensure all affected applications are updated promptly. Additional protective measures include implementing strict input validation for font data, utilizing sandboxing techniques for font processing components, and deploying intrusion detection systems that monitor for unusual memory access patterns. Security professionals should consider implementing application whitelisting policies that restrict font file processing to trusted sources only, and organizations should conduct regular vulnerability assessments to identify and remediate similar issues in their software dependencies. The remediation aligns with ATT&CK technique T1059 Command and Scripting Interpreter and T1203 Exploitation for Client Execution, where proper input validation and patch management serve as primary defensive controls against such exploitation vectors.