CVE-2014-9657 in FreeType
Summary
by MITRE
The tt_face_load_hdmx function in truetype/ttpload.c in FreeType before 2.5.4 does not establish a minimum record size, which allows remote attackers to cause a denial of service (out-of-bounds read) or possibly have unspecified other impact via a crafted TrueType font.
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Analysis
by VulDB Data Team • 03/08/2022
The vulnerability identified as CVE-2014-9657 resides within the FreeType font rendering library, specifically in the tt_face_load_hdmx function located in truetype/ttpload.c. This flaw represents a classic buffer over-read condition that occurs when processing TrueType font files, particularly those containing hdmx (horizontal device metrics) tables. The issue stems from the function's failure to validate the minimum required record size before attempting to parse the hdmx table data, creating a scenario where malformed font files can trigger unexpected memory access patterns.
The technical implementation of this vulnerability demonstrates a lack of proper input validation and bounds checking within the font parsing logic. When FreeType encounters a specially crafted TrueType font file with malformed hdmx table data, the tt_face_load_hdmx function attempts to read beyond the allocated buffer boundaries without first verifying that sufficient data exists to support the expected record structure. This condition falls under CWE-129, Input Validation and Representation, and more specifically aligns with CWE-125, Out-of-bounds Read, which is categorized under the broader class of memory safety vulnerabilities.
The operational impact of this vulnerability extends beyond simple denial of service to potentially enable more sophisticated attack vectors. Remote attackers can leverage this weakness by delivering maliciously crafted TrueType font files through various attack vectors including email attachments, web downloads, or compromised websites. When applications using FreeType for font rendering process these malicious fonts, the out-of-bounds read can result in application crashes, leading to denial of service conditions, or in some cases, may provide opportunities for information disclosure or even arbitrary code execution depending on the specific implementation details and memory layout. This vulnerability directly maps to attack techniques described in the MITRE ATT&CK framework under T1203, Exploitation for Client Execution, and T1059, Command and Scripting Interpreter, when considering the broader attack surface.
The remediation strategy for CVE-2014-9657 requires updating to FreeType version 2.5.4 or later, where the developers implemented proper bounds checking and minimum record size validation for the hdmx table processing. Organizations should prioritize patch management for all systems utilizing FreeType libraries, particularly those running web browsers, desktop applications, or any software that processes font files from untrusted sources. Additionally, implementing proper input sanitization and validation for font file processing, along with network-level filtering of font file types where possible, can provide additional defense-in-depth measures against exploitation attempts. The vulnerability highlights the critical importance of proper memory safety practices in font rendering libraries and underscores the need for comprehensive testing of edge cases in font parsing operations to prevent similar issues in the future.