CVE-2025-48918 is a Cross-Site Scripting (XSS) vulnerability identified in the Drupal Simple Klaro module, affecting all versions prior to 1.10.0 (specifically from version 0.0.0 up to but not including 1.10.0). The vulnerability arises due to improper neutralization of input during web page generation, classified under CWE-79. This means that user-supplied input is not adequately sanitized or encoded before being embedded into web pages, allowing an attacker to inject malicious scripts. When exploited, these scripts can execute in the context of the victim's browser, potentially leading to session hijacking, defacement, redirection to malicious sites, or theft of sensitive information such as cookies or credentials. The Simple Klaro module is used within Drupal environments to manage cookie consent banners, which are commonly displayed on websites to comply with privacy regulations. Because this module interacts with user input and dynamically generates web content, improper input handling creates an attack vector. Although no known exploits have been reported in the wild as of the publication date (June 13, 2025), the vulnerability is publicly disclosed and unpatched in affected versions, increasing the risk of exploitation. No CVSS score has been assigned yet, and no official patches or mitigation links are provided at this time. The vulnerability requires no authentication to exploit and can be triggered via crafted input that is reflected or stored and then rendered in the victim's browser. User interaction is typically required in the form of visiting a maliciously crafted page or clicking a link containing the payload. Given the widespread use of Drupal in European organizations, especially for public-facing websites, this vulnerability poses a significant risk if left unaddressed.

For European organizations, the impact of CVE-2025-48918 can be substantial. Drupal is widely used by government agencies, educational institutions, and private enterprises across Europe, many of which rely on the Simple Klaro module for cookie consent management to comply with GDPR and other privacy laws. Exploitation of this XSS vulnerability could lead to unauthorized access to user sessions, enabling attackers to impersonate legitimate users or administrators. This can result in data breaches involving personal data, undermining GDPR compliance and potentially leading to severe regulatory penalties. Additionally, attackers could deface websites or redirect users to phishing or malware distribution sites, damaging organizational reputation and trust. The vulnerability could also be leveraged as a foothold for further attacks within the network if administrative sessions are compromised. Given the strategic importance of many Drupal-powered websites in Europe, including those of critical infrastructure and public services, the threat extends beyond individual organizations to potentially affect national cybersecurity postures.

To mitigate this vulnerability, European organizations should prioritize upgrading the Simple Klaro module to version 1.10.0 or later as soon as it becomes available, as this will contain the necessary input sanitization fixes. Until an official patch is released, organizations can implement strict Content Security Policy (CSP) headers to restrict the execution of inline scripts and untrusted sources, thereby reducing the risk of XSS exploitation. Additionally, input validation and output encoding should be enforced at the application level, especially for any user-controllable parameters that interact with the Simple Klaro module. Web Application Firewalls (WAFs) should be configured to detect and block common XSS attack patterns targeting this module. Regular security audits and penetration testing focusing on XSS vectors in Drupal environments are recommended to identify and remediate similar issues proactively. Organizations should also educate web administrators and developers about the risks of improper input handling and ensure secure coding practices are followed. Monitoring web logs for unusual or suspicious requests related to cookie consent pages can help detect attempted exploitation.