CVE-2025-13986 is a medium-severity authentication bypass vulnerability identified in the Drupal Disable Login Page module, specifically affecting versions prior to 1.1.3. The vulnerability is classified under CWE-288, which involves authentication bypass through alternate paths or channels. This means that an attacker can circumvent the intended authentication mechanisms by accessing the system via a different route or exploiting a logic flaw in the module's handling of login page disabling. The module Disable Login Page is designed to restrict or disable access to the standard Drupal login page, often used to reduce attack surface or enforce alternative authentication flows. However, due to this vulnerability, an attacker with network access and low privileges can bypass authentication controls without requiring user interaction. The CVSS vector (AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N) indicates that the attack is network-based, requires high attack complexity, low privileges, no user interaction, and impacts confidentiality and integrity but not availability. No public exploits have been reported yet, but the vulnerability's presence in a widely used CMS module makes it a concern. The lack of available patches at the time of reporting necessitates immediate attention from administrators to prevent unauthorized access and potential data exposure or manipulation.

For European organizations, this vulnerability poses a risk of unauthorized access to web applications running Drupal with the affected Disable Login Page module. Confidentiality could be compromised if attackers access sensitive user data or administrative functions. Integrity risks arise from potential unauthorized changes to content or configurations. Although availability is not directly impacted, the breach could lead to further attacks or reputational damage. Organizations in sectors such as government, finance, healthcare, and critical infrastructure that rely on Drupal for web presence or internal portals are particularly vulnerable. The medium severity suggests that while exploitation is not trivial, the potential damage from unauthorized access is significant enough to warrant prompt mitigation. The absence of known exploits reduces immediate risk but should not lead to complacency, especially given the widespread use of Drupal across Europe.

1. Immediately update the Disable Login Page module to version 1.1.3 or later once available to apply the official patch. 2. Until patching is possible, restrict network access to the Drupal login endpoints using firewall rules or web application firewalls (WAFs) to limit exposure. 3. Implement IP whitelisting or VPN access for administrative login pages to reduce attack surface. 4. Monitor web server and application logs for unusual access patterns or repeated attempts to access alternate login paths. 5. Employ multi-factor authentication (MFA) on all administrative accounts to mitigate the impact of potential bypasses. 6. Conduct regular security audits and vulnerability scans focusing on Drupal modules and their configurations. 7. Educate development and operations teams about this vulnerability to ensure timely response and awareness.