CVE-2025-12650 is a stored Cross-Site Scripting (XSS) vulnerability identified in the Simple post listing plugin for WordPress, specifically affecting all versions up to and including 0.2. The vulnerability stems from improper neutralization of input during web page generation, classified under CWE-79. The issue lies in the 'class_name' parameter within the postlist shortcode, where user-supplied input is neither adequately sanitized nor escaped before being rendered on web pages. This flaw enables authenticated attackers with contributor-level or higher privileges to inject arbitrary JavaScript code into posts or pages. When other users visit these pages and interact with the injected elements via mouse actions, the malicious scripts execute in their browsers. The vulnerability has a CVSS 3.1 base score of 6.4, reflecting a medium severity level. The attack vector is network-based with low complexity, requiring privileges equivalent to contributor access but no user interaction beyond mouse movement. The scope is changed (S:C), meaning the vulnerability can affect resources beyond the initially compromised component. The impact includes limited confidentiality and integrity loss, such as session hijacking, defacement, or unauthorized actions performed on behalf of users. No patches or fixes are currently available, and no known exploits have been observed in the wild. The vulnerability was reserved in early November 2025 and published in mid-December 2025 by Wordfence. Given the widespread use of WordPress and the plugin's presence in various websites, this vulnerability poses a tangible risk to web properties that have not restricted contributor access or implemented additional input validation controls.

For European organizations, this vulnerability can lead to significant risks including session hijacking, unauthorized actions performed under the guise of legitimate users, defacement of web content, and potential pivoting to further attacks within the network. Organizations relying on WordPress sites with the Simple post listing plugin installed and contributor-level user roles enabled are particularly vulnerable. The attack requires authenticated access, which limits exposure to internal or semi-trusted users, but insider threats or compromised contributor accounts can exploit this flaw. The confidentiality and integrity of user data and site content can be compromised, potentially damaging reputation and trust. Given the medium severity and the ability to affect multiple users through stored XSS, the vulnerability could be leveraged in targeted phishing or social engineering campaigns. Moreover, the lack of a patch increases the window of exposure. European sectors with high web presence such as media, education, and e-commerce are at elevated risk. Compliance with GDPR also means that data breaches resulting from exploitation could lead to regulatory penalties.

1. Immediately restrict contributor-level access to trusted users only and review existing contributor accounts for suspicious activity. 2. Implement strict input validation and output encoding on the 'class_name' parameter in the shortcode, either by custom code or using security plugins that sanitize inputs. 3. Monitor web application logs for unusual script injections or unexpected shortcode parameter values. 4. Disable or remove the Simple post listing plugin if it is not essential until a security patch is released. 5. Educate content contributors about the risks of injecting untrusted content and enforce security best practices in content management. 6. Employ Content Security Policy (CSP) headers to limit the execution of unauthorized scripts on affected sites. 7. Keep WordPress core and all plugins updated regularly and subscribe to vulnerability notifications for timely patching. 8. Conduct periodic security audits and penetration testing focusing on user input handling in web applications.