CVE-2026-82063 in MongoDB
Summary
by MITRE • 09/08/2026
A use-after-free security issue in the cursor management component of MongoDB Server allows an authenticated user to cause a denial of service. Under specific timing conditions during cursor operations, a stale pointer to a freed resource may be retained and subsequently dereferenced during cursor cleanup, leading to a server process crash.
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Analysis
by VulDB Data Team • 09/08/2026
The vulnerability identified in the MongoDB Server represents a critical memory management flaw within its cursor handling subsystem, specifically categorized under CWE-416 as Use After Free. This type of defect occurs when software continues to use a pointer after it has been freed, which typically leads to program instability and can be exploited by attackers to execute arbitrary code or cause system crashes. In the context of MongoDB, this issue is localized to the component responsible for managing database cursors, which are essential mechanisms used to iterate over query results efficiently without loading entire result sets into memory simultaneously. The presence of such a flaw indicates a failure in proper resource lifecycle management, where references to allocated memory blocks were not correctly invalidated or checked before being accessed again during cleanup routines.
The operational mechanics of this vulnerability rely on specific timing conditions inherent to concurrent cursor operations within the database engine. When multiple clients issue queries that generate cursors, MongoDB must manage these resources dynamically as they are opened and closed. Under certain race conditions or rapid state transitions, a stale pointer may remain in memory after the underlying resource has been deallocated by another part of the system. If this dangling reference is subsequently dereferenced during cursor cleanup processes, it results in an invalid memory access event. This sequence of events directly triggers a segmentation fault or similar critical error within the server process, causing immediate termination of the MongoDB instance rather than graceful handling of the erroneous state.
The primary impact of exploiting this vulnerability is a severe denial of service against the affected database infrastructure. Since the exploitation leads to an unhandled exception that crashes the entire server process, all active connections are severed and any ongoing transactions are aborted. This disruption affects not only the attacker but also legitimate users relying on the database for critical applications. The availability impact is significant because restoring service requires manual intervention or automatic restart mechanisms, during which data consistency must be verified to ensure no corruption occurred due to the abrupt shutdown. Furthermore, repeated exploitation could lead to resource exhaustion if the system attempts frequent recovery cycles without addressing the root cause.
Mitigation strategies should focus on both immediate remediation and long-term architectural improvements. The most effective solution is to apply the official patch provided by MongoDB that addresses this specific use-after-free condition in the cursor management code. Administrators must ensure their environments are updated to versions where memory pointers are properly nullified after deallocation or validated before dereferencing during cleanup phases. Additionally, enabling robust monitoring and logging can help detect unusual patterns of cursor creation and destruction that might indicate attempted exploitation attempts. From a broader security perspective, implementing strict authentication controls ensures that only authorized users can interact with sensitive database operations, thereby reducing the attack surface for authenticated threats like this one. Regular code audits focusing on memory safety in C++ components are also recommended to prevent similar defects from being introduced in future releases.