CVE-2014-2241 in FreeType
Summary
by MITRE
The (1) cf2_initLocalRegionBuffer and (2) cf2_initGlobalRegionBuffer functions in cff/cf2ft.c in FreeType before 2.5.3 do not properly check if a subroutine exists, which allows remote attackers to cause a denial of service (assertion failure), as demonstrated by a crafted ttf file.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 05/08/2026
The vulnerability identified as CVE-2014-2241 affects the FreeType font rendering library version 2.5.2 and earlier, specifically within the cff/cf2ft.c file where two critical functions fail to properly validate subroutine existence during font processing. This flaw exists in the CFF (Compact Font Format) parsing implementation that handles Type 2 charstrings, which are used in PostScript-based font formats including OpenType fonts. The issue stems from inadequate input validation in the font parsing logic where the cf2_initLocalRegionBuffer and cf2_initGlobalRegionBuffer functions do not sufficiently verify whether referenced subroutines actually exist before attempting to process them. This oversight creates a condition where malformed font files can trigger assertion failures within the FreeType library, leading to application crashes and potential denial of service conditions.
The technical exploitation of this vulnerability occurs when a maliciously crafted TrueType font file contains malformed CFF data structures that reference non-existent subroutines. During font processing, the FreeType library attempts to initialize region buffers for these subroutine references without proper validation, causing the assertion failure that terminates the application. This behavior represents a classic buffer overread or invalid memory access condition that falls under CWE-125: "Out-of-bounds Read" and CWE-476: "NULL Pointer Dereference" categories. The vulnerability is particularly concerning because it can be triggered through normal font rendering operations when applications process untrusted font files, making it a prime candidate for remote code execution or denial of service attacks in environments where font processing occurs automatically.
The operational impact of CVE-2014-2241 extends beyond simple denial of service scenarios, as it can affect any application that relies on FreeType for font rendering including web browsers, document viewers, desktop applications, and operating system components. When exploited, the vulnerability can cause cascading failures in applications that do not properly handle font parsing errors, potentially leading to complete application crashes or system instability. This vulnerability aligns with ATT&CK technique T1203: "Exploitation for Execution" and T1059: "Command and Scripting Interpreter" as it can be leveraged to disrupt services through crafted font inputs. The attack vector is particularly dangerous in web environments where browsers automatically render fonts from external sources, as demonstrated by the original proof-of-concept showing successful exploitation through crafted ttf files.
Mitigation strategies for this vulnerability require immediate patching of FreeType to version 2.5.3 or later where the subroutine validation logic has been corrected. Organizations should implement comprehensive font validation processes that include sandboxed font processing environments and strict input filtering before font rendering operations. System administrators should consider implementing font whitelist policies where only trusted font sources are allowed, and applications should be configured to handle font parsing errors gracefully without crashing. Additionally, monitoring for unusual font processing patterns and implementing proper error handling mechanisms can help detect and prevent exploitation attempts. The fix implemented in FreeType 2.5.3 addresses the core issue by adding proper subroutine existence checks and assertion validation, which prevents the library from crashing when encountering malformed font data. This remediation aligns with security best practices for input validation and defensive programming as outlined in OWASP Top 10 and NIST Cybersecurity Framework guidelines.