CVE-2025-47786 is a stored Cross-Site Scripting (XSS) vulnerability identified in version 2.5.13 of emlog, an open source website building system. The vulnerability arises from improper input validation and output encoding in the admin comment management functionality. Specifically, the parameter `perpage_num` in the `/admin/comment.php` endpoint is not validated before being stored directly in the `admin_commend_perpage_num` field within the `emlog_options` database table. Because this input is stored without sanitization and later output without filtering, an authenticated user with at least registered privileges can inject malicious JavaScript code. This malicious script is then executed in the browsers of any users who view the affected admin comment page, potentially leading to session hijacking, credential theft, or other client-side attacks. The vulnerability requires the attacker to have some level of authenticated access (registered user) and user interaction (victim must visit the page where the malicious script is rendered). The CVSS 4.0 score is low (1.9), reflecting the limited scope and exploitation complexity. As of the publication date, no official patch has been released, and no known exploits are reported in the wild. This vulnerability falls under CWE-79, which covers improper neutralization of input during web page generation, a common vector for XSS attacks. The vulnerability affects only version 2.5.13 of emlog, and the impact is confined to websites using this specific version without mitigations.

For European organizations using emlog 2.5.13 to build and manage websites, this vulnerability poses a risk primarily to the confidentiality and integrity of user sessions and data. An attacker with registered user access can inject persistent malicious scripts that execute in the browsers of administrators or other users who access the affected comment management page. This can lead to theft of authentication cookies, unauthorized actions performed on behalf of users, or distribution of malware. While the vulnerability does not directly impact availability or server integrity, the reputational damage and potential data breaches resulting from successful exploitation could be significant, especially for organizations handling sensitive user information or operating in regulated sectors such as finance, healthcare, or public services. The requirement for authenticated access and user interaction limits the attack surface but does not eliminate risk, particularly in environments with many registered users or weak account controls. Additionally, the lack of a patch means organizations must rely on compensating controls until an official fix is available.

1. Immediate mitigation should include restricting or auditing registered user permissions to limit who can access the comment management functionality, reducing the risk of malicious input. 2. Implement web application firewall (WAF) rules to detect and block suspicious input patterns targeting the `perpage_num` parameter or script injection attempts in the admin interface. 3. Employ Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts in browsers, mitigating the impact of injected JavaScript. 4. Regularly monitor and review logs for unusual activities related to comment management or parameter manipulation. 5. If feasible, temporarily disable or restrict access to the vulnerable admin comment page until a patch is released. 6. Encourage users to update to a patched version once available and maintain a robust patch management process. 7. Conduct security awareness training for administrators and users about the risks of XSS and safe browsing practices. 8. Consider implementing input validation and output encoding at the application level as a longer-term fix if source code access is available.