CVE-2026-23906 is an authentication bypass vulnerability affecting Apache Druid versions 0.17.0 through 35.x when the druid-basic-security extension is enabled with LDAP authentication configured. The vulnerability occurs if the underlying LDAP server permits anonymous binds, a configuration where the server allows connections without credentials. In this scenario, an attacker can supply a valid username but an empty password, and due to improper validation of LDAP authentication responses, the system incorrectly treats the anonymous bind as a successful authentication. This flaw allows remote, unauthenticated attackers to bypass authentication controls and gain unauthorized access to the Apache Druid cluster. Once inside, attackers can access sensitive data stored in Druid datasources, execute arbitrary queries, manipulate data, and potentially access administrative interfaces if the compromised account has elevated privileges. This leads to a full compromise of confidentiality, integrity, and availability of the Druid deployment. The root cause is the failure to properly reject anonymous LDAP bind attempts during authentication. Immediate mitigation does not require upgrading Druid but involves disabling anonymous binds on the LDAP server, which prevents exploitation. The definitive fix is included in Apache Druid version 36.0.0 and later, which properly rejects anonymous bind attempts during LDAP authentication.

For European organizations, this vulnerability poses a significant risk especially for those relying on Apache Druid for real-time analytics and data warehousing with LDAP-based authentication. Unauthorized access could lead to exposure of sensitive business intelligence data, customer information, and operational metrics. Attackers could manipulate data or disrupt analytics workflows, impacting decision-making and operational continuity. Organizations in sectors such as finance, telecommunications, healthcare, and government—where Apache Druid is often deployed for large-scale data analytics—face heightened risks of data breaches and regulatory non-compliance under GDPR due to unauthorized data access. The ability to access administrative interfaces further exacerbates the threat, potentially allowing attackers to alter configurations or disable security controls. The vulnerability’s exploitation requires no authentication and no user interaction, increasing the likelihood of successful attacks if LDAP servers permit anonymous binds. This could lead to widespread compromise within affected networks, undermining trust and causing financial and reputational damage.

1. Immediately disable anonymous binds on all LDAP servers used for Apache Druid authentication to prevent exploitation without requiring a Druid upgrade. 2. Audit LDAP server configurations across the organization to ensure anonymous binds are not permitted, especially in environments integrated with Apache Druid. 3. Upgrade Apache Druid to version 36.0.0 or later as soon as possible to apply the official fix that properly rejects anonymous bind attempts during LDAP authentication. 4. Implement strict access controls and monitoring on Druid clusters to detect unusual query patterns or unauthorized access attempts. 5. Employ network segmentation and firewall rules to restrict access to LDAP servers and Druid clusters to trusted hosts only. 6. Conduct regular security assessments and penetration tests focusing on authentication mechanisms and LDAP integration. 7. Review and enforce strong password policies and multi-factor authentication where possible to reduce risk from compromised credentials. 8. Maintain up-to-date incident response plans to quickly address any detected exploitation attempts.