CVE-2025-9550 is a Cross-Site Scripting (XSS) vulnerability classified under CWE-79 that affects the Drupal Facets module, specifically versions from 0.0.0 before 2.0.10 and from 3.0.0 before 3.0.1. The vulnerability stems from improper neutralization of user-supplied input during the generation of web pages, allowing an attacker to inject malicious JavaScript code into pages rendered by the Facets module. This can occur when the module fails to sanitize or encode input parameters properly before embedding them into the HTML output. Successful exploitation requires no authentication but does require user interaction, such as a victim clicking a crafted link or visiting a malicious page. The CVSS v3.1 base score is 6.1, indicating a medium severity with the vector AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N, meaning the attack can be launched remotely with low complexity, no privileges, but requires user interaction, and impacts confidentiality and integrity with a scope change. While no known exploits are currently reported in the wild, the vulnerability poses a risk to websites using the affected Facets versions, potentially allowing attackers to steal session tokens, perform actions on behalf of users, or manipulate displayed content. The Facets module is commonly used to enhance search and filtering capabilities on Drupal sites, making it a valuable target for attackers aiming to compromise user trust or gain footholds in web applications.

For European organizations, the impact of CVE-2025-9550 can be significant, particularly for those operating public-facing websites that utilize the Drupal Facets module for search and navigation enhancements. Exploitation could lead to theft of user session cookies, enabling account hijacking, or manipulation of web content to conduct phishing or social engineering attacks. This undermines user trust and can result in reputational damage, regulatory scrutiny under GDPR due to potential data confidentiality breaches, and financial losses. Although availability is not directly affected, the integrity and confidentiality impacts can disrupt business operations and customer relationships. Organizations in sectors such as e-commerce, government, education, and media, which often rely on Drupal, are particularly vulnerable. The scope of affected systems is broad given Drupal’s widespread use in Europe, and the vulnerability’s ability to cross security boundaries (scope change) increases the risk of widespread impact if exploited.

To mitigate CVE-2025-9550, European organizations should immediately upgrade the Drupal Facets module to version 2.0.10 or later, or 3.0.1 or later, where the vulnerability is patched. In addition to patching, implement strict input validation and output encoding on all user-supplied data processed by the Facets module to prevent injection of malicious scripts. Deploy Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts and reduce the impact of any potential XSS attacks. Regularly audit and monitor web application logs for unusual activity indicative of attempted XSS exploitation. Employ web application firewalls (WAFs) with rules tailored to detect and block XSS payloads targeting Drupal modules. Conduct security awareness training for users to recognize and avoid phishing attempts that could trigger XSS payloads. Finally, maintain an up-to-date inventory of Drupal modules and their versions to ensure timely application of security updates.