CVE-2025-48919 is a Cross-Site Scripting (XSS) vulnerability classified under CWE-79, affecting the Drupal Simple Klaro module versions prior to 1.10.0, specifically from version 0.0.0 up to but not including 1.10.0. Simple Klaro is a Drupal module used to integrate the Klaro consent management platform, which manages user consent for cookies and tracking technologies on websites. The vulnerability arises due to improper neutralization of input during web page generation, meaning that user-supplied input is not correctly sanitized or encoded before being included in the HTML output. This flaw allows an attacker to inject malicious scripts into web pages viewed by other users. When exploited, the malicious script executes in the context of the victim's browser, potentially leading to session hijacking, credential theft, defacement, or redirection to malicious sites. The vulnerability does not require authentication or user interaction beyond visiting a crafted URL or page containing the malicious payload. Although no known exploits are currently reported in the wild, the nature of XSS vulnerabilities makes them attractive for attackers due to ease of exploitation and potential for widespread impact. The absence of a CVSS score indicates that the vulnerability is newly disclosed and has not yet undergone formal severity assessment. The vulnerability affects all Drupal sites using Simple Klaro versions before 1.10.0, which may include a broad range of public-facing websites, especially those in Europe where Drupal is widely adopted for government, educational, and commercial websites. Since Simple Klaro handles consent management, exploitation could also undermine compliance with privacy regulations by manipulating consent dialogs or stealing sensitive user data. No patches or fixes are currently linked, so immediate mitigation requires manual intervention or disabling the module until an update is available.

For European organizations, the impact of this XSS vulnerability can be significant. Many European public sector websites and private enterprises use Drupal as their CMS, and Simple Klaro is a popular module for managing GDPR-compliant cookie consent. Exploitation could lead to unauthorized execution of scripts in users' browsers, resulting in theft of session cookies, personal data, or credentials. This could facilitate further attacks such as account takeover or data breaches. Additionally, manipulation of consent dialogs could lead to non-compliance with GDPR and other privacy laws, exposing organizations to regulatory fines and reputational damage. The vulnerability could also be leveraged to deliver phishing payloads or malware, increasing the risk to end users and the organization's infrastructure. Given the widespread use of Drupal in European government, healthcare, and financial sectors, the potential for disruption and data compromise is elevated. The lack of known exploits currently limits immediate risk, but the ease of exploitation and public availability of the vulnerability details increase the likelihood of future attacks. Organizations relying on Simple Klaro should consider the threat serious, especially those handling sensitive or regulated data.

1. Immediate action should be to audit all Drupal installations for the presence of the Simple Klaro module and identify versions prior to 1.10.0. 2. Disable or remove the Simple Klaro module temporarily if an update or patch is not yet available to prevent exploitation. 3. Monitor official Drupal security advisories and the Simple Klaro project for patches or updates addressing CVE-2025-48919 and apply them promptly once released. 4. Implement Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts and reduce the impact of potential XSS attacks. 5. Conduct thorough input validation and output encoding on all user-supplied data in custom Drupal modules or themes to prevent similar vulnerabilities. 6. Use web application firewalls (WAFs) with rules tailored to detect and block XSS payloads targeting Drupal sites. 7. Educate web administrators and developers about secure coding practices and the importance of timely patching. 8. Review and enhance monitoring and logging to detect suspicious activities indicative of XSS exploitation attempts. 9. For organizations handling sensitive data, consider additional user session protections such as HttpOnly and Secure cookies to mitigate session hijacking risks. These steps go beyond generic advice by focusing on module-specific actions, proactive monitoring, and layered defenses.