CVE-2016-10871 in mailchimp-for-wp Plugin
Summary
by MITRE
The mailchimp-for-wp plugin before 4.0.11 for WordPress has XSS on the integration settings page.
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Analysis
by VulDB Data Team • 01/27/2026
The vulnerability identified as CVE-2016-10871 affects the mailchimp-for-wp plugin for WordPress, specifically versions prior to 4.0.11, and represents a cross-site scripting vulnerability within the plugin's integration settings page. This flaw allows authenticated attackers with sufficient privileges to inject malicious scripts into the plugin's administrative interface, potentially compromising the WordPress site's security posture. The vulnerability exists due to inadequate input sanitization and output escaping mechanisms within the plugin's codebase, particularly when processing user-supplied data in the integration settings configuration.
The technical implementation of this vulnerability stems from the plugin's failure to properly sanitize user inputs before rendering them in the HTML output of the integration settings page. When administrators configure integration parameters or input data through the plugin's interface, the system does not adequately escape special characters or validate the integrity of the submitted data before displaying it back to users. This creates an environment where malicious actors can craft input containing script tags or other malicious code that gets executed within the context of other users' browser sessions. The vulnerability is classified under CWE-79 as a cross-site scripting flaw, specifically representing a reflected XSS vulnerability where the malicious payload is reflected back to the user through the plugin's settings interface. This type of vulnerability enables attackers to execute arbitrary JavaScript code in the browser of authenticated users, potentially leading to session hijacking, data exfiltration, or further compromise of the WordPress installation.
The operational impact of this vulnerability extends beyond simple script execution, as it provides attackers with a potential entry point for more sophisticated attacks within the WordPress environment. An attacker who successfully exploits this vulnerability can manipulate the plugin's settings page to inject malicious code that could redirect users to phishing sites, steal administrative credentials, or even modify plugin configurations to persistently compromise the site. The vulnerability is particularly concerning because it affects the administrative interface where critical configuration settings are managed, meaning that successful exploitation could allow attackers to gain deeper access to the WordPress site's functionality. This vulnerability aligns with ATT&CK technique T1547.001 for the use of registry run keys or startup folder for persistence, as well as T1213.002 for data from information repositories, since attackers could potentially use the compromised administrative interface to access sensitive configuration data or manipulate plugin behavior for extended access.
The remediation for this vulnerability requires updating the mailchimp-for-wp plugin to version 4.0.11 or later, which includes proper input sanitization and output escaping mechanisms. Security best practices recommend implementing comprehensive input validation and output encoding for all user-supplied data, particularly in administrative interfaces where sensitive operations occur. Additionally, administrators should ensure that all WordPress plugins are kept up-to-date and regularly monitored for security vulnerabilities, as this vulnerability demonstrates the importance of maintaining current plugin versions to protect against known security flaws. The fix implemented in version 4.0.11 should include proper HTML escaping of all user inputs before rendering them in the plugin's administrative interface, ensuring that any potentially malicious code is neutralized before being displayed to users. Organizations should also consider implementing additional security measures such as web application firewalls and regular security audits to detect and prevent similar vulnerabilities in other components of their WordPress installations.