CVE-2026-120955 in C Driver
Summary
by MITRE • 11/03/2026
The GridFS file download API in the MongoDB C Driver does not check the result of an internal operation under certain error conditions during file retrieval. This can cause the process to terminate when stream operations continue. A user who can influence file download parameters can trigger this condition, which may result in service unavailability for applications using the affected API.
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Analysis
by VulDB Data Team • 11/03/2026
The vulnerability identified within the MongoDB C Driver affects the GridFS file download application programming interface, specifically during the retrieval of files stored via the GridFS specification. This component is responsible for handling large files by splitting them into chunks and managing their sequential reading from the database. The core technical flaw lies in a missing validation check on the return value or status code of an internal operation that occurs under specific error conditions while processing these file streams. In robust software engineering practices, every function call that can potentially fail must have its result verified to ensure state consistency and prevent undefined behavior. However, in this implementation, when certain errors arise during the stream operations, such as network interruptions or database query failures mid-stream, the driver fails to properly inspect the outcome of these internal calls before proceeding with subsequent read operations.
This lack of error handling leads directly to a critical stability issue where the application process terminates unexpectedly. When the underlying operation encounters an anomaly and returns an error state that is ignored by the calling logic, the stream object may enter an invalid or corrupted state. Subsequent attempts to continue reading from this compromised stream trigger a crash rather than gracefully returning an error code to the application developer for handling. This behavior represents a classic instance of improper input validation leading to resource management errors, which aligns with CWE-252: Unchecked Return Value and CWE-754: Improper Check for Unusual or Exceptional Conditions. The severity is heightened because it does not require complex exploitation techniques; rather, it relies on the natural occurrence of transient failures during file transfer operations.
The operational impact of this vulnerability centers primarily on service availability and reliability. Applications relying on the MongoDB C Driver to stream large files from GridFS are susceptible to sudden crashes when these specific error conditions manifest. Since a user or external system can influence file download parameters, such as by manipulating network connectivity or causing database latency spikes during retrieval, they can effectively trigger this crash condition remotely if access controls permit interaction with the affected endpoints. This results in denial of service for the consuming application, potentially disrupting business-critical workflows that depend on continuous data availability. From a threat modeling perspective, this behavior facilitates resource exhaustion and service disruption attacks, mapping to MITRE ATT&CK technique T1499: Endpoint Denial of Service or more broadly to impacts categorized under Availability in the CIA triad.
To mitigate this risk, developers utilizing the affected version of the MongoDB C Driver should prioritize upgrading to a patched release where internal error states are properly validated before stream continuation is attempted. In environments where immediate patching is not feasible, application-level workarounds can be implemented by wrapping GridFS download calls in robust exception handling or retry logic that detects process instability and restarts services gracefully rather than allowing them to crash silently. Additionally, implementing comprehensive logging around file retrieval operations can help identify the specific error conditions triggering these failures, allowing for targeted monitoring and alerting on potential denial-of-service attempts. Ensuring that all stream-related API calls include explicit checks for failure states is a fundamental security best practice that prevents such logic errors from escalating into system-wide outages.