CVE-2023-2004 in Freetype
Summary
by MITRE • 04/15/2023
An integer overflow vulnerability was discovered in Freetype in tt_hvadvance_adjust() function in src/truetype/ttgxvar.c.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 05/03/2023
The integer overflow vulnerability identified as CVE-2023-2004 resides within the FreeType font rendering library, specifically within the tt_hvadvance_adjust() function located in the src/truetype/ttgxvar.c source file. This critical flaw manifests in the handling of TrueType font variations where the library processes horizontal and vertical advance values for font glyphs. The vulnerability arises when the software attempts to perform arithmetic operations on integer values that exceed their maximum representable bounds, leading to unexpected behavior and potential exploitation opportunities.
The technical implementation of this vulnerability stems from inadequate input validation and boundary checking within the font variation processing logic. When FreeType encounters certain malformed or specially crafted TrueType font files containing excessive advance values, the integer overflow occurs during the calculation of glyph positioning parameters. This flaw operates at the intersection of software security and font rendering, where the library's assumption about valid input ranges becomes compromised by maliciously constructed font data. The overflow can result in memory corruption, where adjacent memory locations are overwritten with unexpected values, potentially leading to arbitrary code execution or application crashes.
The operational impact of CVE-2023-2004 extends across numerous applications and systems that rely on FreeType for font rendering operations. This includes web browsers, desktop applications, mobile operating systems, and server environments that process untrusted font content. Attackers can exploit this vulnerability by delivering maliciously crafted font files through various attack vectors such as email attachments, web downloads, or compromised websites. The vulnerability aligns with CWE-190, which specifically addresses integer overflow conditions, and represents a classic example of how font processing libraries can become attack surfaces. The flaw particularly affects systems where applications automatically render fonts without proper sanitization of font data, creating opportunities for privilege escalation or denial of service attacks.
Mitigation strategies for this vulnerability require immediate patching of affected FreeType versions and implementation of proper input validation at multiple layers within font processing pipelines. System administrators should prioritize updating FreeType libraries to versions that contain the patched tt_hvadvance_adjust() function, which includes enhanced integer overflow protection mechanisms. Additionally, organizations should implement font sanitization processes that validate and normalize font data before processing, particularly for applications handling untrusted content. The ATT&CK framework categorizes this vulnerability under T1203, which covers exploitation of software vulnerabilities, and T1059, involving command and scripting interpreters, as attackers may leverage this flaw to execute malicious code through compromised font rendering processes. Network segmentation and application whitelisting can provide additional defensive layers to limit the potential impact of successful exploitation attempts.