CVE-2017-14919 in Node.js
Summary
by MITRE
Node.js before 4.8.5, 6.x before 6.11.5, and 8.x before 8.8.0 allows remote attackers to cause a denial of service (uncaught exception and crash) by leveraging a change in the zlib module 1.2.9 making 8 an invalid value for the windowBits parameter.
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Analysis
by VulDB Data Team • 01/21/2021
The vulnerability identified as CVE-2017-14919 represents a critical denial of service weakness in Node.js versions prior to specific patches. This issue stems from an improper handling of input validation within the zlib module, which is a core component of Node.js used for data compression and decompression operations. The flaw manifests when the windowBits parameter receives an invalid value of 8, causing the application to throw an uncaught exception that ultimately leads to system crash. This vulnerability affects multiple Node.js release lines including version 4.x below 4.8.5, 6.x below 6.11.5, and 8.x below 8.8.0, indicating a widespread impact across the Node.js ecosystem.
The technical root cause of this vulnerability lies in the zlib module's inadequate parameter validation mechanism. When developers pass an invalid windowBits value of 8 to zlib functions, the underlying compression library fails to properly handle this edge case, resulting in an unhandled exception that terminates the Node.js process. This behavior aligns with CWE-248, which describes exposure of an uncaught exception, and demonstrates how improper error handling can lead to system instability. The vulnerability operates at the application level, where the Node.js runtime fails to gracefully manage malformed input parameters, creating a pathway for attackers to disrupt service availability through controlled input manipulation.
The operational impact of CVE-2017-14919 extends beyond simple service interruption, as it can be exploited to create persistent denial of service conditions in applications that rely heavily on compression functionality. Attackers can leverage this vulnerability by crafting specific requests that include the invalid windowBits parameter, causing Node.js processes to crash repeatedly and forcing system administrators to restart services manually. This vulnerability particularly affects web applications, APIs, and services that process user-provided data through compression functions, making it a significant concern for organizations running Node.js applications in production environments. The exploitability of this vulnerability places it within the ATT&CK framework under the T1499.004 technique for Network Denial of Service, as it specifically targets application-level service availability.
Organizations affected by this vulnerability should prioritize immediate patching of their Node.js installations to versions that address the zlib parameter validation issue. The recommended mitigation strategy involves updating to Node.js 4.8.5, 6.11.5, or 8.8.0, depending on the current version in use. Additionally, implementing input validation measures at the application level can provide defense-in-depth protection against similar issues. System administrators should monitor for signs of exploitation attempts and consider implementing process monitoring to automatically restart crashed Node.js instances. Security teams should also review their incident response procedures to ensure rapid handling of denial of service events, as this vulnerability can be particularly disruptive in high-availability environments where service uptime is critical for business operations.