CVE-2025-58630 is a medium severity vulnerability classified as CWE-79, which refers to Improper Neutralization of Input During Web Page Generation, commonly known as Cross-site Scripting (XSS). This vulnerability affects the rbaer Simple Matomo Tracking Code product, specifically versions up to 1.1.0. The issue allows for Stored XSS attacks, meaning that malicious input submitted by an attacker is stored by the application and later rendered in web pages without proper sanitization or encoding. This enables attackers to execute arbitrary JavaScript code in the context of users' browsers when they view the affected pages. The CVSS 3.1 base score is 5.9, indicating a medium severity level. The vector string (CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:L) shows that the attack can be performed remotely over the network with low attack complexity, but requires high privileges and user interaction. The scope is changed (S:C), meaning the vulnerability affects components beyond the initially vulnerable component. The impact affects confidentiality, integrity, and availability to a limited extent. No known exploits are currently reported in the wild, and no patches have been linked yet. The vulnerability arises because the Simple Matomo Tracking Code does not properly neutralize or encode user-supplied input before embedding it into web pages, allowing malicious scripts to persist and execute in users' browsers. This can lead to session hijacking, defacement, or redirection to malicious sites, undermining user trust and potentially exposing sensitive data.

For European organizations using the Simple Matomo Tracking Code, this vulnerability poses a risk of client-side attacks that can compromise user data confidentiality and integrity. Stored XSS can be leveraged to steal session cookies, perform actions on behalf of authenticated users, or deliver malware. Organizations in sectors with strict data protection regulations such as GDPR (e.g., finance, healthcare, e-commerce) may face compliance risks and reputational damage if user data is compromised. The requirement for high privileges to exploit the vulnerability somewhat limits the attack surface to users with elevated access, such as administrators or content managers, but the impact remains significant if exploited. The change in scope indicates that the vulnerability could affect other components or services relying on the tracking code, potentially amplifying the damage. Additionally, the need for user interaction means that social engineering or phishing could be used to trigger the exploit. Given the widespread use of Matomo analytics in Europe as a privacy-focused alternative to Google Analytics, organizations relying on this tracking code may be targeted, especially those with public-facing websites that collect user data. The absence of known exploits in the wild currently reduces immediate risk but does not eliminate the potential for future attacks once exploit code becomes available.

1. Immediate mitigation should include reviewing and restricting high-privilege user access to the Simple Matomo Tracking Code administration interfaces to reduce the risk of malicious input submission. 2. Implement strict input validation and output encoding on all user-supplied data before rendering it in web pages, using context-appropriate encoding (e.g., HTML entity encoding). 3. Apply Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts and reduce the impact of XSS attacks. 4. Monitor logs and user activity for suspicious input or behavior indicative of attempted XSS exploitation. 5. If possible, temporarily disable or limit the use of the vulnerable tracking code until an official patch or update is released by the vendor. 6. Educate administrators and content managers about the risks of injecting untrusted content and the importance of sanitizing inputs. 7. Regularly update and patch the Simple Matomo Tracking Code once a fix becomes available, and subscribe to vendor security advisories for timely notifications. 8. Conduct security testing, including automated scanning and manual code reviews, to identify and remediate similar vulnerabilities in custom or third-party code.