CVE-2024-37433 in Mailster Plugin
Summary
by MITRE • 07/22/2024
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in EverPress Mailster mailster.This issue affects Mailster: from n/a through <= 4.0.9.
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Analysis
by VulDB Data Team • 04/02/2026
The CVE-2024-37433 vulnerability represents a critical cross-site scripting flaw in the Mailster email marketing plugin for WordPress, specifically impacting versions through 4.0.9. This vulnerability falls under the CWE-79 category of Cross-Site Scripting, which occurs when web applications fail to properly sanitize user input before incorporating it into dynamically generated web pages. The flaw manifests in the web page generation process where input data is not adequately neutralized, creating an avenue for malicious actors to inject harmful scripts into web content that will execute in the contexts of other users.
The technical nature of this vulnerability stems from the plugin's insufficient validation and sanitization of user-supplied data within its web page rendering mechanisms. When users interact with the Mailster plugin interface or when email templates are processed, the system fails to properly escape or encode input parameters before they are rendered in HTML output. This allows attackers to craft malicious payloads that can be executed when other users view affected pages or interact with the compromised plugin functionality. The vulnerability is particularly concerning because it operates at the point of web page generation, meaning that any user input that flows through the plugin's processing pipeline could potentially serve as an attack vector.
The operational impact of this vulnerability extends beyond simple script execution, as it can enable attackers to perform a wide range of malicious activities including session hijacking, credential theft, data exfiltration, and privilege escalation within the affected WordPress environment. Attackers could leverage this XSS vulnerability to inject malicious JavaScript code that would execute in the browsers of unsuspecting users who visit pages containing the compromised content. This could result in unauthorized access to user accounts, modification of website content, redirection to malicious sites, or even the installation of additional malware. The vulnerability's presence in the Mailster plugin means that any WordPress site using this email marketing solution is potentially at risk, especially if the site has multiple users or admin privileges.
Mitigation strategies for CVE-2024-37433 should prioritize immediate patching of the affected Mailster plugin to version 4.1.0 or later, as this represents the official fix for the identified XSS vulnerability. Organizations should implement comprehensive input validation and output encoding mechanisms throughout their web applications, ensuring that all user-supplied data is properly sanitized before being incorporated into web page content. Security measures should include the implementation of Content Security Policy headers to limit script execution, regular security audits of plugin and theme code, and the maintenance of up-to-date security monitoring systems. The vulnerability aligns with ATT&CK technique T1566.001 for initial access through web shell, and T1059.007 for command and scripting interpreter for JavaScript execution. Organizations should also consider implementing web application firewalls and conducting thorough penetration testing to identify similar vulnerabilities in their web applications, while maintaining strict version control and regular update procedures for all WordPress plugins and themes.