CVE-2019-19981 in Email Subscribers
Summary
by MITRE
The WordPress plugin, Email Subscribers & Newsletters, before 4.2.3 had a flaw that allowed for CSRF to be exploited on all plugin settings.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 03/17/2024
The WordPress plugin Email Subscribers & Newsletters version 4.2.2 and earlier contained a critical cross-site request forgery vulnerability that exposed all plugin settings to unauthorized modification. This vulnerability falls under the Common Weakness Enumeration category CWE-352, which specifically addresses cross-site request forgery flaws in web applications. The flaw existed due to the absence of proper anti-CSRF tokens in the plugin's administrative interfaces, allowing attackers to execute malicious requests on behalf of authenticated users without their knowledge or consent.
The technical implementation of this vulnerability stemmed from the plugin's failure to validate request origins and implement proper CSRF protection mechanisms in its settings management endpoints. When administrators accessed the plugin's configuration pages, the application did not verify that requests originated from legitimate sources within the same session, creating an exploitable gap in the authentication and authorization framework. Attackers could craft malicious web pages or leverage social engineering techniques to trick authenticated users into performing unintended actions on the vulnerable plugin settings, potentially leading to complete compromise of the newsletter subscription management functionality.
The operational impact of this vulnerability extended beyond simple configuration changes, as it allowed attackers to modify critical plugin parameters that controlled email delivery, subscriber management, and newsletter scheduling. This could result in unauthorized email campaigns, subscriber data manipulation, or complete disruption of the newsletter service. The vulnerability was particularly concerning because it affected all plugin settings, meaning attackers could potentially gain control over the entire email subscription management system. The flaw persisted across all supported WordPress versions where the vulnerable plugin was installed, making it a widespread concern for WordPress administrators managing email marketing functionalities.
Mitigation strategies for this vulnerability required immediate patching to version 4.2.3 or later, which implemented proper CSRF token validation mechanisms. System administrators should also review and audit all plugin installations for similar vulnerabilities, implementing additional security measures such as role-based access controls and monitoring for unauthorized configuration changes. The incident highlighted the importance of proper input validation and request origin verification in WordPress plugin development, aligning with ATT&CK framework technique T1059.001 for command and scripting interpreter usage, as attackers could leverage this vulnerability to establish persistent access through compromised email systems. Organizations should also consider implementing web application firewalls and regular security audits to identify and remediate similar CSRF vulnerabilities in their WordPress environments, particularly focusing on administrative interfaces that handle sensitive configuration data.