CVE-2026-18696 in MongoDB
Summary
by MITRE • 08/11/2026
An issue in MongoDB Server's applyOps command could allow an authenticated user with specific non-default privileges to perform certain data-definition operations, such as dropping or modifying collections, against collections they do not have permission to manipulate. This is due to an inconsistency in how the target collection is determined between the authorization check and the actual operation.
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Analysis
by VulDB Data Team • 08/11/2026
This vulnerability resides within the MongoDB database server implementation where a privilege escalation flaw exists in the applyOps command functionality. The security issue stems from an authorization bypass mechanism that occurs when the system performs collection validation during the authorization check phase versus the actual execution phase. When an authenticated user possesses specific non-default privileges, they can exploit this inconsistency to execute data-definition operations against collections they should not normally have access to, effectively circumventing standard access controls.
The technical flaw manifests as a mismatch in collection identification logic between the authorization verification process and the operational execution context. During the authorization check, MongoDB evaluates permissions based on one collection reference while the actual applyOps command operates on a different collection target determined through an alternative code path. This discrepancy creates a window where malicious operations can proceed despite insufficient privileges for the target collection. The vulnerability specifically affects scenarios where users have certain administrative capabilities but lack full database access rights.
Operational impact of this vulnerability extends beyond simple privilege escalation as it enables authenticated attackers to perform destructive data-definition operations including dropping collections, modifying schema structures, and potentially corrupting database integrity. The affected environment must have specific non-default privilege configurations for exploitation to be possible, making it less likely to occur in default installations but still posing significant risk in properly configured enterprise environments. Attackers could leverage this vulnerability to cause data loss, disrupt services, or gain unauthorized access to sensitive information stored within collections they normally couldn't manipulate.
Mitigation strategies should focus on implementing proper privilege management and access control enforcement within MongoDB deployments. Organizations should review and restrict the use of applyOps command privileges, ensuring that only trusted administrative accounts possess the necessary permissions for such operations. Regular security audits should verify that authorization checks align with operational execution paths, preventing inconsistencies between permission validation and actual implementation. This vulnerability aligns with CWE-284 Access Control Issues and could be categorized under ATT&CK technique T1078 Valid Accounts for maintaining persistent access within compromised database environments.
The root cause of this issue demonstrates a fundamental flaw in authorization model consistency where the system fails to maintain uniform collection identification across different operational phases. This inconsistency represents a classic security boundary violation where authorization checks don't properly reflect the actual execution context, creating opportunities for privilege escalation attacks. Database administrators should consider implementing additional monitoring and logging for applyOps operations to detect potential exploitation attempts, as well as ensuring that MongoDB server configurations follow security best practices and principle of least privilege principles.
Security patches addressing this vulnerability typically involve synchronizing collection identification between authorization checks and operational execution contexts, ensuring that both phases reference the same target collection. This fix requires careful implementation to maintain existing functionality while closing the authorization gap that enables the bypass. Organizations should prioritize patching affected MongoDB installations and conduct thorough testing to ensure that the security fix doesn't introduce regressions in legitimate administrative operations. The vulnerability highlights the importance of maintaining consistent security controls across all system phases, particularly when handling sensitive data-definition operations that could compromise database integrity and availability.
This issue represents a critical concern for database administrators managing MongoDB deployments with complex privilege structures, as it demonstrates how subtle implementation inconsistencies can create significant security risks. The vulnerability requires careful attention to privilege assignment policies and regular validation of access controls to prevent unauthorized escalation. Security teams should implement continuous monitoring for unusual applyOps activity patterns and maintain up-to-date knowledge of MongoDB security advisories to proactively address similar issues that may arise in the future.