CVE-2026-1850 in Server
Summary
by MITRE • 02/10/2026
Complex queries can cause excessive memory usage in MongoDB Query Planner resulting in an Out-Of-Memory Crash.
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Analysis
by VulDB Data Team • 02/26/2026
The vulnerability identified as CVE-2026-1850 represents a critical memory exhaustion issue within MongoDB's query planning mechanism that can lead to system instability and potential service disruption. This flaw specifically affects the MongoDB Query Planner component which is responsible for analyzing and optimizing complex database queries before execution. The vulnerability manifests when the system processes intricate query structures that require excessive memory allocation during the planning phase, ultimately resulting in out-of-memory conditions that can crash the MongoDB instance.
The technical root cause of this vulnerability lies in the insufficient memory management and resource allocation controls within MongoDB's query planning algorithms. When the Query Planner encounters complex queries with multiple nested conditions, subqueries, or elaborate join operations, it may allocate memory resources without proper bounds checking or memory consumption limits. This behavior creates a path where malicious or poorly constructed queries can trigger unbounded memory growth, causing the MongoDB process to exhaust available system memory and subsequently crash. The vulnerability operates at the intersection of query optimization and memory management, where the planner's resource estimation fails to account for the exponential memory requirements of certain query patterns.
The operational impact of CVE-2026-1850 extends beyond simple service disruption to encompass potential data integrity concerns and business continuity risks. Organizations relying on MongoDB for critical applications face significant operational challenges when this vulnerability is exploited, as the resulting crashes can lead to data loss, transaction failures, and extended downtime. The vulnerability is particularly concerning in environments where MongoDB handles high-volume transactional workloads or serves as a backend for applications with dynamic query generation capabilities. Attackers could potentially exploit this vulnerability through crafted queries to perform denial-of-service attacks against MongoDB instances, while legitimate applications might inadvertently trigger the issue through complex analytical queries or poorly optimized database operations.
This vulnerability maps to CWE-401: Improper Release of Memory Before Removal from Heap, which specifically addresses memory management failures in software systems. The issue also aligns with ATT&CK technique T1499.004: Endpoint Denial of Service, which focuses on causing system instability through resource exhaustion attacks. Organizations should implement immediate mitigations including query validation and resource limits, while also considering MongoDB version updates that address the underlying memory management issues. The recommended approach involves establishing query execution time limits, implementing memory consumption monitoring, and deploying query optimization strategies that prevent the execution of overly complex queries. Additionally, system administrators should configure appropriate memory limits for MongoDB processes and implement robust monitoring solutions to detect anomalous memory usage patterns that could indicate exploitation attempts.