CVE-2018-20853 in MailPoet Newsletters Plugin
Summary
by MITRE
An issue was discovered in the MailPoet Newsletters (aka wysija-newsletters) plugin before 2.8.2 for WordPress. The plugin is vulnerable to SPAM attacks.
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Analysis
by VulDB Data Team • 11/07/2019
The vulnerability identified as CVE-2018-20853 affects the MailPoet Newsletters plugin for WordPress, specifically versions prior to 2.8.2, creating a significant security weakness that enables spam attacks. This issue resides within the plugin's handling of user input and newsletter submission processes, where inadequate validation and sanitization mechanisms allow malicious actors to exploit the system for spam distribution. The vulnerability represents a critical flaw in the plugin's architecture that directly impacts the integrity and security of WordPress installations using this newsletter service.
The technical implementation of this vulnerability stems from insufficient input validation within the plugin's email submission and newsletter creation functions. Attackers can leverage this weakness to inject malicious content into the newsletter submission forms, enabling them to send spam emails through the compromised WordPress installation. The flaw operates by bypassing standard security controls that should validate email addresses, content filtering, and submission rate limiting mechanisms. This allows spammers to abuse the legitimate newsletter functionality for unauthorized mass email campaigns, potentially leading to the compromise of the entire WordPress installation and its associated email infrastructure.
The operational impact of this vulnerability extends beyond simple spam generation, as it creates a vector for more sophisticated attacks including phishing campaigns, malware distribution, and reputation damage to affected websites. WordPress installations using vulnerable versions of MailPoet become unwitting participants in spam networks, potentially leading to blacklisting by email providers and loss of sender reputation. The vulnerability also poses risks to end users who may receive spam emails from compromised sites, creating trust issues and potential security exposure for recipients. Organizations relying on these newsletter systems face regulatory compliance challenges and potential legal ramifications from spam-related activities conducted through their platforms.
Security mitigation strategies for this vulnerability require immediate patching to version 2.8.2 or later, which includes enhanced input validation and spam prevention mechanisms. System administrators should implement additional monitoring of newsletter submission activities to detect unusual patterns or excessive email volumes that may indicate exploitation attempts. The implementation of rate limiting controls and more robust email validation processes provides additional defense layers against similar attacks. Organizations should also conduct comprehensive security audits of their WordPress installations to identify other potentially vulnerable plugins and ensure proper access controls are in place. This vulnerability aligns with CWE-20, which describes improper input validation, and represents a clear example of how plugin vulnerabilities can create widespread security impacts in content management systems. The ATT&CK framework categorizes this as a technique involving spam email delivery through compromised web applications, emphasizing the importance of securing web application components that handle user-generated content and email functionality.