CVE-2025-65186 identifies a stored Cross Site Scripting (XSS) vulnerability in Grav CMS version 1.7.49. The vulnerability arises from improper sanitization of <script> tags within the Markdown editor used by authenticated users to edit page content. When a user with editing privileges inserts malicious JavaScript code into the page content, the payload is stored persistently and executed whenever the affected page is viewed in the admin interface. This stored XSS flaw allows attackers to execute arbitrary scripts in the context of the CMS admin panel, potentially leading to session hijacking, privilege escalation, or unauthorized actions within the CMS environment. The vulnerability requires the attacker to have authenticated access to the CMS and some user interaction (viewing the malicious page). The CVSS 3.1 base score is 6.1, reflecting medium severity with network attack vector, low attack complexity, no privileges required, but user interaction needed, and partial confidentiality and integrity impact. No patches or exploits are currently publicly available, but the vulnerability is published and should be addressed promptly. The CWE-79 classification confirms this is a classic XSS issue related to improper input validation and output encoding in web applications.

For European organizations, this vulnerability poses a risk primarily to the confidentiality and integrity of content managed via Grav CMS. Attackers with authenticated access can inject malicious scripts that execute in the admin interface, potentially allowing session hijacking or unauthorized administrative actions. This can lead to defacement, data leakage, or further compromise of internal systems if the CMS is integrated with other enterprise services. The impact is heightened in organizations with multiple content editors or where CMS credentials are shared or weakly managed. Although availability is not directly affected, the trustworthiness of the CMS and its content can be undermined, impacting business operations and reputation. Given Grav CMS's usage in various sectors including media, education, and small to medium enterprises, the threat is relevant where Grav CMS is deployed for critical content management.

1. Immediately restrict access to the Grav CMS page editor to trusted and trained personnel only, minimizing the number of users with editing privileges. 2. Monitor and audit all content changes in the CMS for suspicious scripts or unusual edits. 3. Implement additional input validation and output encoding at the application or web server level to sanitize <script> tags and other potentially malicious inputs in Markdown content. 4. Deploy Web Application Firewalls (WAFs) with rules to detect and block stored XSS payloads targeting Grav CMS interfaces. 5. Encourage strong authentication mechanisms such as multi-factor authentication (MFA) for CMS users to reduce risk from compromised credentials. 6. Stay alert for official patches or updates from Grav CMS developers and apply them promptly once released. 7. Educate CMS users on the risks of injecting untrusted content and safe editing practices. 8. Consider isolating the CMS admin interface behind VPN or IP whitelisting to reduce exposure.