CVE-2025-49890 is a medium-severity vulnerability classified under CWE-79, which pertains to improper neutralization of input during web page generation, commonly known as Cross-site Scripting (XSS). This specific vulnerability affects the AWStats Script developed by Jorge Garcia de Bustos, versions up to 0.3. The vulnerability allows for Stored XSS attacks, where malicious input is persistently stored by the application and later rendered in web pages without proper sanitization or encoding. This can enable an attacker to execute arbitrary JavaScript code in the context of the victim's browser 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, meaning the vulnerability affects resources 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 from insufficient input validation and output encoding in the AWStats Script, which is a web analytics tool used to generate statistics from server logs. Stored XSS can lead to session hijacking, defacement, or redirection to malicious sites, potentially compromising user data and trust in the affected web application.

For European organizations using AWStats Script for web analytics, this vulnerability poses a risk of persistent cross-site scripting attacks that can compromise the confidentiality and integrity of user sessions and data. Attackers with high privileges on the system could inject malicious scripts that execute whenever a user accesses the affected analytics pages, potentially leading to session theft, unauthorized actions, or distribution of malware. This can undermine the reliability of web analytics data and damage organizational reputation. Given that AWStats is often used in hosting environments and by IT departments for monitoring web traffic, exploitation could also facilitate lateral movement or further compromise within the network. The impact is particularly relevant for organizations subject to strict data protection regulations such as GDPR, as exploitation could lead to unauthorized access or leakage of personal data, resulting in legal and financial consequences.

To mitigate this vulnerability, organizations should: 1) Apply any available patches or updates from the AWStats project as soon as they are released. Since no patch links are currently provided, monitoring official sources for updates is critical. 2) Implement strict input validation and output encoding on all user-supplied data within the AWStats Script, ensuring that any data rendered in web pages is properly sanitized to prevent script injection. 3) Restrict access to the AWStats interface to trusted users only, using network segmentation, VPNs, or IP whitelisting to limit exposure. 4) Employ Content Security Policy (CSP) headers to reduce the impact of potential XSS by restricting the sources of executable scripts. 5) Conduct regular security audits and penetration tests focusing on web application vulnerabilities, including XSS, especially in internal tools like AWStats. 6) Educate privileged users about the risks of XSS and the importance of cautious interaction with analytics dashboards. 7) Monitor logs for unusual activity that could indicate exploitation attempts. These measures go beyond generic advice by focusing on the specific context of AWStats usage and the nature of the vulnerability.