MongoDB C Driver BSON JSON Parsing Numeric Conversion Error
CVE-2026-84963 Published on September 3, 2026
Silent field truncation via unchecked int cast of huge JSON string values in JSON-to-BSON parser
An incorrect numeric conversion in the JSON parsing component of the MongoDB C Driver's BSON library may cause an unusually large text value to be silently shortened, or the corresponding field to be omitted, while the parsing operation still reports success and returns no error. An unauthenticated party who can supply the input processed by an application that uses this component may cause that application to hold data that does not match what was submitted, which may result in unintended alteration of data.
Vulnerability Analysis
CVE-2026-84963 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity and availability.
Weakness Type
Incorrect Conversion between Numeric Types
When converting from one data type to another, such as long to integer, data can be omitted or translated in a way that produces unexpected values. If the resulting values are used in a sensitive context, then dangerous behaviors may occur.
Products Associated with CVE-2026-84963
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Affected Versions
MongoDB C Driver:- Version 1.10.0 and below 1.30.9 is affected.
- Version 2.0.0 and below 2.5.2 is affected.