CVE-2018-11440 in Liblouis
Summary
by MITRE
Liblouis 3.5.0 has a stack-based Buffer Overflow in the function parseChars in compileTranslationTable.c.
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Analysis
by VulDB Data Team • 03/17/2023
The vulnerability CVE-2018-11440 represents a critical stack-based buffer overflow flaw discovered in Liblouis version 3.5.0, a widely-used braille translation library that converts text to braille and vice versa. This library serves as a fundamental component in accessibility software for the visually impaired, making the vulnerability particularly concerning from both security and accessibility perspectives. The flaw manifests within the parseChars function located in the compileTranslationTable.c source file, indicating that the issue occurs during the compilation phase of translation tables rather than during runtime execution.
The technical nature of this vulnerability stems from improper input validation and memory management within the parseChars function. When Liblouis processes translation table files containing malformed or excessively long character sequences, the function fails to properly bounds-check buffer allocations, allowing attackers to write beyond allocated memory boundaries. This stack-based overflow creates a condition where adjacent memory locations can be overwritten, potentially leading to arbitrary code execution, application crashes, or denial of service conditions. The vulnerability is classified under CWE-121 Stack-based Buffer Overflow, which specifically addresses buffer overflows occurring in stack memory regions.
From an operational standpoint, this vulnerability poses significant risks to systems utilizing Liblouis for braille translation services. Attackers could exploit this flaw by crafting malicious translation table files that trigger the buffer overflow when processed by vulnerable versions of the library. The impact extends beyond simple application instability, as successful exploitation could allow attackers to execute arbitrary code with the privileges of the affected application, potentially compromising entire systems. Given that Liblouis is integrated into various accessibility tools, e-commerce platforms, and educational software, the attack surface is broad and includes both enterprise and consumer environments. The vulnerability aligns with ATT&CK technique T1059.007 for Command and Scripting Interpreter, as exploitation may involve crafting malicious input that triggers the overflow during normal library operations.
Mitigation strategies for CVE-2018-11440 primarily involve immediate patching of affected systems with updated versions of Liblouis that contain proper bounds checking and input validation. Organizations should prioritize updating their installations to Liblouis version 3.6.0 or later, which includes the necessary fixes for this vulnerability. Additionally, implementing input sanitization measures and restricting file access to trusted translation table sources can provide defense-in-depth. System administrators should monitor for any signs of exploitation attempts and consider implementing application whitelisting policies that restrict execution of untrusted translation table files. The vulnerability demonstrates the importance of maintaining up-to-date accessibility libraries and underscores the need for proper memory safety practices in critical system components that serve essential functions for users with disabilities.