CVE-2025-5539 identifies a stored Cross-Site Scripting (XSS) vulnerability in the Simple Contact Form Plugin for WordPress – WP Easy Contact, versions up to and including 4.0.0. The vulnerability stems from improper neutralization of input during web page generation, specifically within the 'emd_mb_meta' shortcode. The plugin fails to adequately sanitize and escape user-supplied attributes, allowing authenticated users with contributor-level permissions or higher to inject arbitrary JavaScript code into pages. Because the malicious script is stored and executed whenever any user accesses the infected page, this can lead to persistent XSS attacks. The attack vector is remote over the network, with low attack complexity and no user interaction required beyond page access. The scope is changed as the vulnerability affects the confidentiality and integrity of user data, potentially enabling session hijacking, privilege escalation, or redirection to malicious sites. The vulnerability does not impact availability. Although no known exploits have been reported in the wild, the risk is significant due to the widespread use of WordPress and the plugin. The vulnerability is tracked under CWE-79 (Improper Neutralization of Input During Web Page Generation). The CVSS v3.1 base score is 6.4, reflecting medium severity. No official patches have been linked yet, so mitigation requires careful access control and input validation measures.

The vulnerability allows attackers with contributor-level access to inject persistent malicious scripts into WordPress pages, which execute in the context of any user visiting those pages. This can lead to session hijacking, theft of sensitive information, unauthorized actions performed on behalf of users, and potential defacement or redirection attacks. For organizations, this undermines the confidentiality and integrity of user data and can damage reputation and trust. Since contributor-level access is sufficient, insider threats or compromised contributor accounts pose a significant risk. The lack of required user interaction for exploitation increases the likelihood of successful attacks. While availability is not directly affected, the broader security compromise can lead to service disruptions or escalated attacks. The vulnerability affects all sites using the plugin up to version 4.0.0, which may be numerous given WordPress's market share. Without patches, organizations remain exposed to targeted or opportunistic attacks.

1. Immediately restrict contributor-level user permissions to trusted individuals and audit existing contributor accounts for suspicious activity. 2. Disable or remove the Simple Contact Form Plugin – WP Easy Contact until a patched version is released. 3. Implement Web Application Firewall (WAF) rules to detect and block malicious payloads targeting the 'emd_mb_meta' shortcode parameters. 4. Employ Content Security Policy (CSP) headers to limit the execution of unauthorized scripts on affected pages. 5. Monitor logs for unusual activity or injection attempts related to the plugin. 6. Educate content contributors about safe input practices and the risks of injecting untrusted content. 7. Once available, promptly apply official patches or updates from the vendor. 8. Consider alternative contact form plugins with a strong security track record if immediate patching is not feasible. 9. Conduct regular security assessments and vulnerability scans focusing on WordPress plugins. 10. Use security plugins that can detect and remediate stored XSS vulnerabilities.