CVE-2018-25047 in Smarty
Summary
by MITRE • 09/15/2022
In Smarty before 3.1.47 and 4.x before 4.2.1, libs/plugins/function.mailto.php allows XSS. A web page that uses smarty_function_mailto, and that could be parameterized using GET or POST input parameters, could allow injection of JavaScript code by a user.
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Analysis
by VulDB Data Team • 11/05/2025
The vulnerability identified as CVE-2018-25047 represents a cross-site scripting flaw within the Smarty template engine affecting versions prior to 3.1.47 and 4.x prior to 4.2.1. This issue specifically resides in the libs/plugins/function.mailto.php file which is responsible for generating email links within web applications utilizing Smarty templating. The flaw enables attackers to inject malicious JavaScript code through parameterized input that gets processed by the mailto function, creating a persistent XSS vector that can compromise user sessions and execute unauthorized commands.
The technical implementation of this vulnerability stems from insufficient input sanitization within the Smarty mailto plugin functionality. When web applications incorporate user-supplied data into the mailto function parameters without proper validation or encoding, the template engine fails to adequately escape special characters that could be interpreted as HTML or JavaScript code. This weakness allows attackers to inject script tags, event handlers, or other malicious payloads that execute in the context of other users' browsers when they view pages containing the compromised mailto links.
From an operational impact perspective, this vulnerability poses significant risks to web applications that rely on Smarty for dynamic content generation and user interaction. The XSS vulnerability can be exploited to steal session cookies, perform unauthorized actions on behalf of users, redirect victims to malicious websites, or even deface web pages. Attackers can leverage this vulnerability through various means including crafted URLs with malicious parameters or by injecting code through POST requests that get processed by the mailto function. The widespread adoption of Smarty as a template engine in content management systems, web applications, and enterprise software platforms amplifies the potential impact of this vulnerability across numerous organizations.
The vulnerability aligns with CWE-79 Cross-site Scripting weakness classification, specifically addressing the failure to sanitize user input before incorporating it into web page content. From an ATT&CK framework perspective, this vulnerability maps to T1566 Initial Access through the use of malicious links or web content, and T1059 Command and Control through the potential for executing malicious JavaScript code. Organizations should prioritize immediate remediation by upgrading to Smarty versions 3.1.47 or 4.2.1 and implementing proper input validation and output encoding practices. Additional mitigations include implementing Content Security Policy headers, using proper HTML escaping for all user-supplied content, and conducting regular security assessments of template processing functions to identify similar vulnerabilities in other components of the web application stack.