---
id: CVE-2026-84963
title: >-
  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 …
summary: >-
  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 …
severity: medium
cvss: 5.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N'
cwe:
  - CWE-681
vendor: mongodb
product: c_driver
affected:
  - 'c_driver >= 1.10.0, < 1.30.9'
  - 'c_driver >= 2.0.0, < 2.5.2'
patched:
  - c_driver 2.5.2
published: '2026-09-03'
updated: '2026-09-22'
sourceUpdated: '2026-09-22T16:22:04.710'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-84963'
references:
  - url: 'https://jira.mongodb.org/browse/CDRIVER-6407'
    label: cna@mongodb.com
tags:
  - nvd
epss: 0.0031
epssPercentile: 0.21218
ingestedAt: '2026-09-22T17:07:07.357Z'
---

## Overview

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.

## Affected

- `c_driver >= 1.10.0, < 1.30.9`
- `c_driver >= 2.0.0, < 2.5.2`

## Remediation

Upgrade past the affected range:

- `c_driver 2.5.2`