CVE-2026-18690 in Server
Summary
by MITRE • 08/11/2026
An issue in MongoDB Server could allow an authenticated user with a limited database-scoped role to perform an action against protected system collections that their assigned privileges should not permit. This could result in critical system collections being dropped and recreated without proper authorization.
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Analysis
by VulDB Data Team • 08/11/2026
This vulnerability represents a significant privilege escalation flaw within MongoDB server implementations that directly contravenes the principle of least privilege enforcement. The issue manifests when authenticated users possess database-scoped roles that should restrict their access to system collections, yet they can still execute destructive operations against these protected resources. The technical root cause stems from insufficient authorization checks during collection manipulation operations, particularly those involving system collections such as system.users, system.roles, or other metadata repositories that control database security state. This weakness creates a pathway for malicious actors with limited database permissions to bypass intended access controls and execute unauthorized administrative actions.
The operational impact of this vulnerability extends far beyond simple privilege escalation as it enables attackers to fundamentally compromise database integrity and availability. When an authenticated user can drop and recreate critical system collections, they effectively gain the ability to modify authentication credentials, alter role assignments, and manipulate database security configurations without proper authorization. This capability directly maps to attack techniques described in the mitre ATT&CK framework under privilege escalation and defense evasion tactics, where adversaries seek to maintain persistent access while avoiding detection through legitimate administrative functions. The vulnerability particularly affects environments where role-based access control is implemented but not properly enforced at the system collection level.
Security professionals should recognize this issue as a variant of CWE-284 Access Control Bypass, which specifically addresses insufficient access control mechanisms that allow unauthorized access to protected resources. The flaw demonstrates inadequate input validation and authorization enforcement within MongoDB's internal security model, where database-scoped privileges fail to properly translate into system-level access restrictions. Organizations implementing MongoDB should immediately review their user role assignments and ensure proper segregation of duties, particularly for administrative functions that involve system collections. The vulnerability emphasizes the critical importance of comprehensive testing for privilege boundaries and proper authorization enforcement in database systems.
Mitigation strategies should focus on immediate patch application from MongoDB vendors to address the specific authorization bypass mechanism. Additionally, organizations must implement regular access control reviews and establish monitoring procedures for unauthorized system collection modifications. Security teams should consider implementing database activity monitoring solutions that can detect suspicious patterns involving system collection operations. The vulnerability also highlights the need for robust configuration management practices where database administrators carefully audit role definitions and ensure that privileges are properly scoped to prevent such cross-level access violations. Organizations should also consider implementing additional security controls such as mandatory access controls or enhanced logging mechanisms that provide visibility into privilege escalation attempts and unauthorized administrative actions against protected resources.