CVE-2023-4772 in Newsletter Plugin
Summary
by MITRE • 09/07/2023
The Newsletter plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'newsletter_form' shortcode in versions up to, and including, 7.8.9 due to insufficient input sanitization and output escaping on user supplied attributes. This makes it possible for authenticated attackers with contributor-level and above permissions to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.
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Analysis
by VulDB Data Team • 04/10/2026
The vulnerability identified as CVE-2023-4772 affects the Newsletter plugin for WordPress, specifically targeting versions up to and including 7.8.9. This represents a critical security flaw that undermines the integrity of web applications built on the WordPress platform. The vulnerability manifests through the 'newsletter_form' shortcode, which serves as an entry point for malicious actors to exploit the system. The issue stems from inadequate input validation mechanisms and insufficient output escaping procedures that fail to properly sanitize user-supplied data before processing. This weakness creates a persistent security risk that can be exploited by attackers who possess contributor-level privileges or higher within the WordPress environment.
The technical implementation of this vulnerability follows a classic stored cross-site scripting pattern where malicious code injection occurs during the processing of user input rather than during runtime execution. When legitimate users interact with pages containing the compromised shortcode, the injected scripts execute in their browsers without their knowledge or consent. The vulnerability operates at the application layer, specifically within the plugin's handling of shortcode parameters and attribute processing. Attackers can leverage this flaw to perform unauthorized actions including but not limited to session hijacking, data exfiltration, and redirection to malicious websites. The stored nature of this XSS vulnerability means that once the malicious payload is injected, it persists in the system and affects all users who view the affected pages, making the impact particularly severe for content management systems where multiple users interact with shared content.
From an operational perspective, this vulnerability significantly impacts the security posture of WordPress installations using the affected plugin. The requirement for contributor-level access or higher reduces the attack surface compared to vulnerabilities requiring administrator privileges, yet still represents a substantial risk since contributors often have the ability to publish and modify content. The attack chain typically involves an authenticated attacker creating malicious content through the newsletter form shortcode, which then gets stored in the database and executed whenever other users access pages containing this content. This creates a persistent threat vector that can be exploited repeatedly without requiring additional authentication. The vulnerability affects not only the immediate users of the newsletter plugin but potentially the entire WordPress site's user base, as the injected scripts can manipulate browser sessions and access sensitive data. The impact extends beyond simple script execution to include potential data breaches, unauthorized access to user accounts, and compromise of the overall web application security.
The security implications of CVE-2023-4772 align with common weakness enumerations found in the CWE database, particularly CWE-79 which addresses Cross-Site Scripting vulnerabilities. This classification reflects the core issue of insufficient input sanitization and output escaping in web applications. The vulnerability also maps to several ATT&CK framework techniques including T1566 for social engineering and T1071 for application layer protocols, as the attack exploits legitimate application functionality to deliver malicious payloads. Organizations affected by this vulnerability should immediately implement mitigations including updating to the patched version of the Newsletter plugin, implementing proper input validation measures, and conducting thorough security audits of all installed plugins. Additionally, administrators should consider implementing web application firewalls and monitoring systems to detect suspicious shortcode usage patterns. The remediation process must include not only patching the vulnerable plugin but also reviewing and strengthening input validation procedures across all user-supplied content processing within the WordPress environment. This vulnerability demonstrates the critical importance of maintaining up-to-date security practices and the potential for seemingly minor plugin flaws to create substantial security risks in complex web applications.