CVE-2015-8862 in mustache Package
Summary
by MITRE
mustache package before 2.2.1 for Node.js allows remote attackers to conduct cross-site scripting (XSS) attacks by leveraging a template with an attribute that is not quoted.
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Analysis
by VulDB Data Team • 05/14/2026
The vulnerability identified as CVE-2015-8862 affects the mustache package version 2.2.1 and earlier in Node.js environments, presenting a significant cross-site scripting risk that can be exploited by remote attackers. This flaw specifically manifests when templates contain unquoted attributes, creating a pathway for malicious code injection that bypasses standard security controls. The issue stems from the package's insufficient sanitization of template attributes during rendering processes, allowing attackers to inject malicious scripts that execute in the context of the victim's browser.
The technical root cause of this vulnerability lies in the improper handling of HTML attribute values within mustache template syntax. When developers fail to properly quote template attributes, the mustache rendering engine does not adequately sanitize the input before incorporating it into the final HTML output. This creates a scenario where attacker-controlled data can be injected into HTML attributes, leading to XSS exploitation. The vulnerability aligns with CWE-79, which defines Cross-site Scripting as a weakness where untrusted data is incorporated into web pages without proper validation or sanitization. The flaw operates at the application layer, specifically within the template rendering subsystem of the Node.js package ecosystem.
The operational impact of this vulnerability extends beyond simple script execution, as it can enable attackers to perform a range of malicious activities including session hijacking, data theft, and redirection to malicious sites. Remote attackers can leverage this vulnerability by crafting malicious templates that contain unquoted attributes, which then get rendered into web pages viewed by unsuspecting users. The attack vector is particularly concerning because it can be initiated through template manipulation without requiring direct access to the application's codebase, making it difficult to detect and prevent through traditional code review processes. This vulnerability affects web applications that rely on mustache templates for dynamic content generation and user interface rendering.
Mitigation strategies for CVE-2015-8862 involve immediate patching of the mustache package to version 2.2.1 or later, which includes proper attribute sanitization and validation mechanisms. Organizations should implement comprehensive input validation for all template attributes, ensuring that all attribute values are properly quoted and escaped before rendering. The implementation of Content Security Policy headers can provide additional protection by restricting the sources from which scripts can be loaded, thereby limiting the impact of potential XSS exploitation. Security teams should also conduct regular vulnerability assessments and code audits specifically targeting template rendering components, as outlined in the ATT&CK framework's web application attacks category. Furthermore, developers should be trained on secure template usage practices and the importance of proper attribute quoting to prevent similar vulnerabilities in future development cycles.