CVE-2026-9740
Received Received - Intake
MongoDB Server BSON Validation Recursion Denial of Service

Publication date: 2026-06-09

Last updated on: 2026-06-09

Assigner: MongoDB, Inc.

Description
A vulnerability in MongoDB Server's BSON validation logic allows an unauthenticated user to crash the mongod process by sending a specially crafted message. The BSON validator's handling of certain nested binary data structures permits uncontrolled mutual recursion between validation functions, where each re-entry resets internal depth tracking.
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Meta Information
Published
2026-06-09
Last Modified
2026-06-09
Generated
2026-06-10
AI Q&A
2026-06-10
EPSS Evaluated
N/A
NVD
CVE-2026-9740
EUVD
EUVD-2026-35857
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
mongodb mongodb_server *
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-674 The product does not properly control the amount of recursion that takes place, consuming excessive resources, such as allocated memory or the program stack.
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Executive Summary

This vulnerability exists in MongoDB Server's BSON validation logic. It allows an unauthenticated user to crash the mongod process by sending a specially crafted message. The issue arises because the BSON validator improperly handles certain nested binary data structures, leading to uncontrolled mutual recursion between validation functions. Each recursive call resets internal depth tracking, which can cause the process to crash.

Impact Analysis

The vulnerability can cause a denial of service by crashing the mongod process. Since it can be triggered by an unauthenticated user remotely, it may lead to service interruptions, affecting availability of the MongoDB server.

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