CVE-2026-9750: MongoDB Authenticated Denial of Service and Data Integrity Issue

Technical summary

This vulnerability stems from insufficient input validation and namespace confusion (CWE-617) in MongoDB's query execution layer. When processing certain document structures, user-controlled fields can interfere with internal metadata that MongoDB relies on during query optimization and result generation. An authenticated attacker can craft specially formed documents that trigger either a denial of service (crash) or data integrity issues (incorrect results). The vector indicates network accessibility with low attack complexity, but requires valid authentication credentials.

Business impact

Organizations running MongoDB face two distinct risks: service disruption from intentional server crashes, and silent data corruption where queries return wrong results without obvious indication of failure. The latter poses particular risk in financial, healthcare, or analytics contexts where data accuracy is critical and users may not immediately detect anomalies. Recovery from crashes requires administrative intervention; data corruption may go unnoticed and propagate downstream.

Affected systems

MongoDB installations are affected. Verify your specific deployment version against the official MongoDB security advisory to confirm which releases are vulnerable. Both on-premises and cloud-managed MongoDB instances using affected versions require attention.

Exploitability

Exploitation requires valid database credentials—an insider threat, compromised application account, or credential theft scenario. It is not remotely exploitable via unauthenticated access. The attack has low complexity once authenticated, requiring only document creation using standard MongoDB operations. Organizations with strict credential hygiene and least-privilege access controls reduce but do not eliminate this risk.

Remediation

Apply the security patch released by MongoDB addressing this metadata validation issue. Implement or strengthen database access controls: enforce strong authentication, restrict database user accounts to minimum required privileges, and monitor for unusual document creation patterns or query anomalies. Credential rotation is advisable if compromise is suspected.

Patch guidance

Consult the official MongoDB security advisory for affected version numbers and corresponding patched releases. Apply patches during a maintenance window, testing in a staging environment first to ensure application compatibility. If patching is delayed, restrict database access to trusted application accounts only and implement compensating controls such as read-only modes where operationally feasible.

Detection guidance

Monitor MongoDB logs for unusual document structures or repeated query failures. Track authentication events and failed queries that return unexpected results or error messages. Alert on any unexpected server restarts or crashes correlated with specific user accounts. In analytics or reporting pipelines, implement data reconciliation checks to catch silent result corruption early.

Why prioritize this

While classified as medium severity, prioritize this based on your deployment's exposure: if untrusted users have database accounts, or if compromised application credentials are plausible, escalate priority. Data integrity issues may pose higher long-term risk than crashes depending on your compliance posture and downstream data usage.

Risk score, explained

CVSS 6.5 (Medium) reflects high impact on availability (crash scenarios) combined with requirement for valid authentication. The absence of confidentiality or integrity scoring in the vector may underweight silent data corruption risk; assess this vulnerability against your own data sensitivity and access control maturity.

Frequently asked questions