BSON Deserialization Bypass in MongoDB

Executive Summary

This vulnerability involves a bypass in the BSON serialization component's type-restriction control. The check for compiler-generated types uses an overly permissive heuristic, allowing unauthorized parties to supply BSON content that constructs unintended types when deserialized. This can lead to unexpected object states and errors in application logic without requiring elevated privileges.

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Detection Guidance

Detection requires analyzing BSON deserialization processes in applications using the MongoDB C# Driver. Monitor logs for deserialization errors or unexpected object states. Check for unusual input data in network traffic directed to MongoDB endpoints. No specific commands are provided in the context.

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Impact Analysis

An attacker could exploit this to manipulate application behavior by injecting unauthorized data into deserialized objects. This may cause crashes, incorrect processing, or unintended data exposure, depending on how the application uses the deserialized content.

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Compliance Impact

This vulnerability could potentially lead to unauthorized data manipulation or exposure if exploited, which may violate compliance requirements under GDPR (data integrity and confidentiality) and HIPAA (protected health information integrity). The ability to bypass deserialization controls may allow unauthorized parties to alter application state or inject malicious data, risking non-compliance with data protection principles.

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Mitigation Strategies

Update the MongoDB C# Driver to the latest version that patches this issue. Restrict deserialization to trusted BSON content by implementing strict type checks. Validate all BSON input before deserialization. Monitor application behavior for signs of exploitation.

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