CVE-2018-6191 in MuJS
Summary
by MITRE
The js_strtod function in jsdtoa.c in Artifex MuJS through 1.0.2 has an integer overflow because of incorrect exponent validation.
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Analysis
by VulDB Data Team • 12/30/2024
The vulnerability identified as CVE-2018-6191 resides within the js_strtod function located in the jsdtoa.c file of Artifex MuJS JavaScript interpreter version 1.0.2 and earlier. This function is responsible for converting string representations of floating-point numbers into their binary floating-point equivalents, a critical operation in any JavaScript engine. The flaw manifests as an integer overflow condition that stems from inadequate validation of exponent values during the string-to-double conversion process.
The technical implementation issue occurs when the js_strtod function processes numeric strings that contain excessively large or malformed exponent values. The function fails to properly validate the range of exponent values before performing arithmetic operations that could exceed the bounds of the integer data types used internally. This validation gap allows attackers to craft specially formatted numeric strings that trigger integer overflow conditions during the parsing phase. When the exponent value exceeds the maximum representable integer value, the arithmetic operations overflow and produce unexpected results that can corrupt the parsing state or cause the interpreter to behave unpredictably.
The operational impact of this vulnerability extends beyond simple parsing failures, as it creates potential pathways for arbitrary code execution within the context of applications that utilize MuJS. Since MuJS is a lightweight JavaScript interpreter often embedded in applications, the vulnerability could be exploited through crafted input in web applications, mobile apps, or embedded systems that rely on this interpreter. The integer overflow condition may lead to memory corruption, stack smashing, or other undefined behaviors that attackers could potentially leverage to execute malicious code. This vulnerability particularly affects environments where untrusted input is processed through the JavaScript interpreter, making it a significant concern for web applications and software systems that integrate MuJS for scripting capabilities.
Mitigation strategies for CVE-2018-6191 should prioritize updating to version 1.0.3 or later of Artifex MuJS, where the exponent validation has been corrected to prevent integer overflow conditions. Organizations should also implement input validation measures that sanitize numeric string inputs before processing them through the JavaScript interpreter, particularly in applications that handle untrusted data. The vulnerability aligns with CWE-190, which catalogs integer overflow conditions, and could potentially map to ATT&CK techniques involving code injection or privilege escalation through interpreter vulnerabilities. Additionally, runtime protections such as address space layout randomization and stack canaries should be enabled to reduce the exploitability of any remaining vulnerabilities in the system.