CVE-2017-1000188 in nodejs ejs
Summary
by MITRE
nodejs ejs version older than 2.5.5 is vulnerable to a Cross-site-scripting in the ejs.renderFile() resulting in code injection
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Analysis
by VulDB Data Team • 01/10/2023
The vulnerability identified as CVE-2017-1000188 affects Node.js EJS (Embedded JavaScript) template engine versions prior to 2.5.5, presenting a critical cross-site scripting vulnerability within the ejs.renderFile() function that enables remote code execution. This flaw resides in the template rendering process where user-supplied input is not properly sanitized before being processed through the rendering engine, creating a dangerous pathway for attackers to inject malicious code that executes on the server or client side.
The technical implementation of this vulnerability stems from inadequate input validation and sanitization within the EJS template engine's rendering pipeline. When the ejs.renderFile() method processes templates containing untrusted user data, it fails to properly escape or filter special characters that could be interpreted as executable code. This weakness allows attackers to craft malicious template content that, when rendered, executes arbitrary JavaScript code in the context of the web application. The vulnerability manifests when template variables are directly inserted into the rendered output without proper HTML escaping or context-aware encoding, enabling attackers to inject script tags, event handlers, or other malicious payloads that can execute in the victim's browser or on the server.
The operational impact of this vulnerability extends beyond simple XSS attacks to encompass full remote code execution capabilities, making it particularly dangerous for web applications that rely on dynamic template rendering. Attackers can leverage this vulnerability to execute arbitrary commands on the server hosting the vulnerable application, potentially leading to complete system compromise, data exfiltration, or further lateral movement within the network. The vulnerability affects both server-side and client-side rendering contexts, depending on how the template engine is configured and deployed, creating multiple attack vectors for threat actors. Organizations running vulnerable EJS versions face significant risk of unauthorized access, data breaches, and system compromise, particularly in environments where user input is processed through template rendering functions.
Mitigation strategies for CVE-2017-1000188 require immediate patching of all affected EJS installations to version 2.5.5 or later, which includes proper input sanitization and output encoding mechanisms. Organizations should implement comprehensive input validation at multiple layers of their applications, ensuring that all user-supplied data is properly escaped before being processed through template engines. Security configurations should enforce strict content security policies and disable unnecessary template features that could contribute to code injection risks. The vulnerability aligns with CWE-79 (Cross-site Scripting) and CWE-94 (Code Injection) categories, and maps to ATT&CK techniques including T1059.007 (Command and Scripting Interpreter: JavaScript) and T1566 (Phishing) for initial access vectors. Additionally, organizations should conduct thorough security assessments of their web applications to identify other potential template injection points and implement proper security monitoring to detect anomalous template processing activities that could indicate exploitation attempts.