CVE-2026-82057 in MongoDB
Summary
by MITRE • 09/08/2026
A security issue was discovered in MongoDB where an authenticated user with readWrite privileges could crash the mongod server process. By specifying a custom WiredTiger storage configuration option with an incompatible value during collection creation, a user could cause a type confusion in the storage engine layer. When documents were subsequently read from the misconfigured collection, the resulting mismatch in expected data format led to corrupted memory interpretation and a server crash. The crafted collection configuration persists across restarts, requiring manual operator intervention to remediate.
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Analysis
by VulDB Data Team • 09/08/2026
A critical vulnerability has been identified within MongoDB that allows an authenticated user with write privileges to cause a denial of service against the database server process. This flaw resides in the WiredTiger storage engine layer and is triggered by the creation of collections with specific, incompatible configuration options. The issue stems from a type confusion error where the system fails to properly validate or handle mismatched data formats during subsequent read operations on the misconfigured collection. When documents are accessed from such a collection, the internal memory interpretation becomes corrupted due to this format discrepancy, leading directly to the termination of the mongod process. This represents a significant risk for environments where multiple users share database instances with varying levels of access control, as it enables any user possessing readWrite privileges on a specific namespace to disrupt service availability without requiring elevated administrative rights or exploiting authentication bypasses.
The technical root cause involves improper validation of storage engine configuration parameters during collection initialization. WiredTiger relies on strict schema and format consistency for efficient data retrieval and memory management. By injecting an incompatible value into the custom storage options, the attacker forces the database to allocate resources based on incorrect assumptions about document structure or encoding. Subsequent read operations attempt to parse these documents using standard expectations that conflict with the actual stored format. This mismatch results in a type confusion scenario where pointers are dereferenced incorrectly or memory buffers are accessed out of bounds, causing immediate instability and crash of the database daemon. The persistence of this misconfiguration across server restarts exacerbates the impact, as the service will fail to start correctly or will crash immediately upon attempting to load data from the affected collection until manual intervention occurs.
From a risk management perspective, this vulnerability aligns with CWE-120 Buffer Copy without Checking Size of Input and CWE-787 Out-of-bounds Write in certain interpretations of memory corruption leading to crashes. In terms of adversary behavior, it maps to ATT&CK technique T1499 Endpoint Denial of Service, specifically through resource exhaustion or service disruption via application-level flaws rather than network flooding. The impact is primarily a denial of service condition affecting availability, which can lead to significant operational downtime and potential data loss if the crash occurs during critical write transactions that are not properly committed before termination.
Mitigation strategies must focus on both immediate remediation and long-term prevention. Administrators should audit existing collections for any custom WiredTiger configurations introduced by application code or manual operations. If a vulnerable collection is identified, it requires manual intervention to either drop the collection entirely if data can be recovered from backups or recreate it with valid configuration parameters after migrating necessary documents to a new, correctly configured collection. To prevent future occurrences, organizations should implement strict input validation within their database interaction layers to ensure that only approved and validated storage options are passed during collection creation. Additionally, applying the latest security patches provided by MongoDB is essential as they often include enhanced validation logic for configuration parameters. Regular monitoring of server logs for unexpected process terminations can also aid in early detection of such exploitation attempts before widespread service disruption occurs.