CVE-2026-82066 in MongoDB
Summary
by MITRE • 09/08/2026
A heap out-of-bounds read security issue exists in the query planning component of MongoDB Server. An authenticated user with database read and write privileges can trigger the security issue through crafted query operations, causing the server to read memory beyond allocated buffer boundaries. The revealed memory contents may be partially observable through diagnostic query statistics output.
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Analysis
by VulDB Data Team • 09/08/2026
The vulnerability identified in the MongoDB Server query planning component represents a critical heap-based out-of-bounds read condition that compromises the integrity of data processing during query execution. This flaw resides within the logic responsible for analyzing and optimizing database queries, specifically when handling complex or malformed request structures. The root cause is an insufficient validation mechanism regarding buffer boundaries during memory allocation and access operations. When the server processes a specially crafted query operation, it fails to correctly verify that the requested data indices remain within the limits of the allocated heap memory segment. This oversight allows the application to read from memory addresses adjacent to or beyond the intended buffer, leading to an information disclosure scenario where sensitive internal state or potentially other process memory contents are exposed.
The operational impact of this vulnerability is significant due to its potential for remote code execution precursors and severe data leakage. Although the immediate effect described involves reading memory beyond allocated boundaries, such out-of-bounds reads can reveal cryptographic keys, authentication tokens, or proprietary application logic stored in adjacent heap regions. The description notes that these revealed contents may be partially observable through diagnostic query statistics output, which provides an indirect but effective channel for exfiltrating data. This side-channel effect means that even if the raw memory dump is not directly returned to the user, statistical anomalies or timing differences derived from accessing different memory locations can leak information about the server's internal state. For organizations relying on MongoDB for critical data storage, this undermines confidentiality guarantees and could facilitate further attacks by providing attackers with valuable intelligence about the system architecture and security controls.
From a threat modeling perspective, this vulnerability aligns with CWE-125, which defines out-of-bounds read errors where software reads past the end of an allocated buffer. It also relates to CWE-200, concerning exposure of sensitive information to an unauthorized actor. In terms of adversary tactics, this flaw supports techniques associated with ATT&CK technique T1003, specifically Credential Dumping or OS Credential Dumping if the exposed memory contains authentication material, and potentially T1567 for Exfiltration Over Alternative Protocol if the diagnostic output is used as a covert channel. The requirement for an authenticated user with database read and write privileges limits the attack surface to insider threats or compromised accounts rather than unauthenticated remote attackers. However, given that many production environments grant broad access rights to application service accounts, this restriction does not eliminate risk but rather shifts it from external network attacks to internal lateral movement scenarios following initial compromise.
Mitigation strategies must focus on both immediate remediation and long-term architectural hardening. The primary defense is the deployment of vendor-provided security patches that address the boundary checks within the query planner module. Organizations should prioritize updating their MongoDB instances to versions where this heap overflow logic has been corrected with rigorous input validation and bounds checking routines. In addition to patching, implementing strict least-privilege access controls is essential to minimize the impact if a vulnerability is exploited in other components. Database administrators should audit user roles to ensure that service accounts do not possess unnecessary write privileges unless explicitly required for application functionality. Furthermore, enabling comprehensive logging and monitoring of query patterns can help detect anomalous behavior indicative of exploitation attempts, such as unusually large or complex queries being processed by the planner. Regular security assessments and penetration testing focused on database interaction layers will further strengthen defenses against similar memory corruption vulnerabilities in future software updates.