CVE-2025-52035 is a stored Cross-Site Scripting (XSS) vulnerability identified in NotesCMS, specifically affecting the /index.php?route=notes page. The vulnerability arises from improper sanitization or validation of the title field within service descriptions, allowing an attacker to inject malicious scripts that are stored persistently on the server. When a legitimate user accesses the affected page, the malicious script executes in their browser context, potentially leading to session hijacking, credential theft, or unauthorized actions performed on behalf of the user. The vulnerability was confirmed in the source code as of commit 7d821a0f028b0778b245b99ab3d3bff1ac10e2d3 dated May 8, 2024, and was fixed in commit 95322c5121dbd7070f3bd54f2848079654a0a8ea dated March 31, 2025. The attack can be launched remotely without authentication, increasing the risk of exploitation. Although no known exploits are currently reported in the wild, the nature of stored XSS vulnerabilities makes them attractive targets for attackers aiming to compromise user sessions or conduct phishing attacks within the context of the vulnerable application. The absence of a CVSS score indicates that the vulnerability has not yet been fully assessed for severity, but the technical details suggest a significant risk due to the persistent nature of the XSS and the lack of required authentication for exploitation.

For European organizations using NotesCMS, this vulnerability poses a significant risk to the confidentiality and integrity of user data and sessions. Stored XSS can lead to unauthorized access to sensitive information, including user credentials and personal data, which is particularly critical under the GDPR framework. The exploitation of this vulnerability could result in data breaches, reputational damage, and potential regulatory penalties. Additionally, attackers could leverage the vulnerability to perform actions on behalf of users, potentially disrupting business operations or spreading malware within the organization. Since the vulnerability can be exploited remotely without authentication, it increases the attack surface and the likelihood of successful attacks, especially in environments where NotesCMS is publicly accessible or used by multiple users with varying privilege levels.

European organizations should immediately verify if they are running vulnerable versions of NotesCMS and apply the patch introduced in commit 95322c5121dbd7070f3bd54f2848079654a0a8ea dated March 31, 2025. If patching is not immediately possible, organizations should implement input validation and output encoding on the title fields to prevent script injection. Employing Content Security Policy (CSP) headers can help mitigate the impact of XSS by restricting the execution of unauthorized scripts. Regular security audits and code reviews focusing on input sanitization should be conducted to detect similar vulnerabilities. Additionally, organizations should educate users about the risks of XSS and monitor web application logs for suspicious activities indicative of exploitation attempts. Deploying Web Application Firewalls (WAFs) with rules targeting XSS payloads can provide an additional layer of defense while patches are being applied.