CVE-2023-5740 in Live Chat with Facebook Messenger Plugin
Summary
by MITRE • 10/25/2023
The Live Chat with Facebook Messenger plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the plugin's 'messenger' shortcode in all versions up to, and including, 1.0 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 • 04/11/2026
The vulnerability identified as CVE-2023-5740 affects the Live Chat with Facebook Messenger plugin for WordPress, representing a critical stored cross-site scripting flaw that has persisted across all versions up to and including 1.0. This vulnerability stems from inadequate input sanitization and output escaping mechanisms within the plugin's messenger shortcode implementation, creating a persistent security weakness that can be exploited by authenticated attackers possessing contributor-level privileges or higher. The flaw allows malicious actors to inject arbitrary web scripts into pages that will execute whenever any user accesses those compromised pages, making it particularly dangerous in multi-user environments where contributors and higher-level users have access to plugin settings.
The technical nature of this vulnerability aligns with CWE-79, which specifically addresses cross-site scripting flaws, and demonstrates how insufficient sanitization of user-supplied attributes can create persistent injection points within web applications. The messenger shortcode serves as the attack vector where user-provided parameters are not properly validated or escaped before being rendered in the web page context, enabling attackers to embed malicious JavaScript code that persists in the database and executes in the context of other users' browsers. This stored XSS vulnerability operates through the principle that user input is directly incorporated into dynamic web content without adequate security controls to prevent script execution.
The operational impact of this vulnerability extends beyond simple data theft or defacement, as it creates a persistent backdoor for attackers to execute arbitrary code within the context of authenticated user sessions. Contributors and higher-level WordPress users typically have access to various plugin configuration options, making this vulnerability particularly dangerous when attackers can leverage their privileges to inject malicious scripts that can then be executed by other users with varying levels of access. The attack surface is amplified because the injected scripts can potentially access cookies, session tokens, or other sensitive information that users might have in their browser context, and could be used to escalate privileges or establish persistent access to the WordPress installation.
Mitigation strategies for CVE-2023-5740 should prioritize immediate plugin updates to versions that address the input sanitization and output escaping deficiencies, while also implementing comprehensive access controls to limit the permissions of contributors and other lower-privileged users who might be able to modify plugin settings. Network-based security controls such as web application firewalls can provide additional protection by monitoring for suspicious script injection patterns, though these measures are secondary to proper code-level fixes. Organizations should also conduct thorough security audits of their WordPress installations to identify any other plugins that might be susceptible to similar vulnerabilities, as this type of flaw often indicates broader security issues within the application ecosystem. The remediation process should include validating all user-supplied input through proper sanitization functions and implementing strict output escaping mechanisms to prevent script execution in web contexts, aligning with security best practices established in the OWASP Top Ten and NIST cybersecurity guidelines.