CVE-2019-19982 in Email Subscribers
Summary
by MITRE
The WordPress plugin, Email Subscribers & Newsletters, before 4.2.3 had a flaw that allowed for unauthenticated option creation. In order to exploit this vulnerability, an attacker would need to send a /wp-admin/admin-post.php?es_skip=1&option_name= request.
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Analysis
by VulDB Data Team • 03/17/2024
The vulnerability identified as CVE-2019-19982 affects the Email Subscribers & Newsletters WordPress plugin, specifically versions prior to 4.2.3, and represents a critical security flaw that undermines the integrity of WordPress site configurations. This vulnerability falls under the category of insecure direct object reference and privilege escalation, as it allows attackers to manipulate plugin options without proper authentication. The flaw exists within the plugin's handling of administrative requests, creating a pathway for unauthorized modification of critical system parameters. The vulnerability is particularly concerning because it operates at the administrative level, potentially enabling attackers to gain deeper control over affected WordPress installations.
The technical exploitation of this vulnerability occurs through a specific endpoint manipulation pattern that leverages the plugin's administrative post handler. Attackers can send a crafted request to the wp-admin/admin-post.php endpoint with specific parameters including es_skip=1 and option_name= which bypasses the normal authentication checks. This allows the attacker to create or modify arbitrary options within the plugin's configuration system, effectively enabling them to inject malicious configuration values or manipulate existing settings. The flaw demonstrates poor input validation and authorization controls within the plugin's administrative interface, as it fails to properly verify that the requesting user possesses appropriate privileges before processing option modifications.
The operational impact of this vulnerability extends beyond simple configuration manipulation, as it can enable attackers to establish persistent access or cause significant disruption to email newsletter functionality. An attacker could potentially modify plugin settings to redirect email submissions to malicious addresses, alter notification configurations, or introduce backdoor functionality within the email subscriber management system. This vulnerability is particularly dangerous when combined with other exploitation techniques, as it can serve as a stepping stone for more advanced attacks. The flaw essentially allows an unauthenticated attacker to perform administrative actions on vulnerable WordPress sites, which aligns with the ATT&CK framework's privilege escalation tactics and can be categorized under CWE-284 for improper access control.
Mitigation strategies for this vulnerability require immediate patching of the Email Subscribers & Newsletters plugin to version 4.2.3 or later, which contains the necessary security fixes to prevent unauthorized option manipulation. System administrators should also implement additional security measures including regular plugin audits, monitoring of wp-admin endpoint access patterns, and implementation of web application firewalls to detect and block suspicious requests. The vulnerability highlights the importance of proper input validation and access control mechanisms in WordPress plugins, as outlined in the OWASP Top Ten security risks and the CWE catalog's emphasis on secure coding practices. Organizations should conduct comprehensive security assessments of their WordPress installations to identify other potentially vulnerable plugins and ensure that all third-party components are regularly updated to address known security flaws.