CVE-2025-5540 in Event RSVP and Simple Event Management Plugin Plugin
Summary
by MITRE • 06/26/2025
The Event RSVP and Simple Event Management Plugin plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the plugin's 'emd_mb_meta' shortcode in all versions up to, and including, 4.1.0 due to insufficient input sanitization and output escaping on user supplied attributes. This makes it possible for authenticated attackers, with contributor-level access and above, 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 • 06/26/2025
The vulnerability identified as CVE-2025-5540 affects the Event RSVP and Simple Event Management Plugin for WordPress, representing a critical stored cross-site scripting flaw that compromises the security of WordPress installations. This vulnerability exists within the plugin's 'emd_mb_meta' shortcode implementation and impacts all versions up to and including 4.1.0, making it a widespread concern for WordPress users who rely on this plugin for event management functionality. The flaw stems from inadequate input sanitization and output escaping mechanisms that fail to properly validate or sanitize user-supplied attributes before processing them within the shortcode context.
The technical nature of this vulnerability allows authenticated attackers with contributor-level privileges or higher to exploit the weakness by injecting malicious scripts through the plugin's shortcode functionality. When legitimate users access pages containing the injected content, the malicious scripts execute in their browsers, potentially leading to session hijacking, data theft, or further exploitation of the compromised systems. This stored XSS vulnerability operates by manipulating the plugin's handling of shortcode attributes, where user-provided data is not adequately sanitized before being rendered in web pages. The vulnerability aligns with CWE-79 which specifically addresses cross-site scripting flaws, and represents a direct violation of secure coding practices that require proper input validation and output encoding.
The operational impact of CVE-2025-5540 extends beyond simple script execution as it provides attackers with persistent access vectors that can be leveraged for more sophisticated attacks. Since the vulnerability requires only contributor-level access, it represents a significant risk for WordPress sites where multiple users have editing privileges, particularly in collaborative environments or sites with less stringent access controls. Attackers can craft malicious shortcodes that remain embedded in the site's content, ensuring that every page load containing the injected scripts results in exploitation. This persistent nature makes the vulnerability particularly dangerous as it can remain undetected for extended periods while continuously compromising user sessions and potentially providing attackers with access to sensitive event data, user information, or administrative functions.
Mitigation strategies for this vulnerability should prioritize immediate patching of the plugin to version 4.1.1 or later, where the sanitization and escaping issues have been addressed. Organizations should also implement additional security measures including regular security audits of installed plugins, monitoring for suspicious shortcode usage, and restricting contributor-level access to only essential functions. Network-based solutions such as web application firewalls can provide additional protection layers, though they should not be relied upon as the sole defense mechanism. The vulnerability demonstrates the critical importance of input validation and output escaping in web applications, aligning with ATT&CK technique T1566 which covers phishing with malicious attachments and links, as attackers can use such vulnerabilities to deliver malicious payloads through seemingly legitimate event management content. Regular security assessments and vulnerability scanning should be implemented to identify similar issues in other plugins and themes, as this vulnerability highlights the need for comprehensive security practices across entire WordPress ecosystems rather than isolated component fixes.