---
id: CVE-2026-84965
title: >-
  An integer wraparound in an allocation size calculation in the BSON library's
  JSON parsing code can cause a buffer to be released while a following copy
  operation still writes through the stale pointer
summary: >-
  An integer wraparound in an allocation size calculation in the BSON library's
  JSON parsing code can cause a buffer to be released while a following copy
  operation still writes through the stale pointer. On builds where sizes are 32
  bits,…
severity: medium
cvss: 5.1
cvssVector: 'CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-190
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: '2026-09-22T16:00:19.730'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-84965'
references:
  - url: 'https://jira.mongodb.org/browse/CDRIVER-6405'
    label: cna@mongodb.com
tags:
  - nvd
epss: 0.00125
epssPercentile: 0.01855
ingestedAt: '2026-09-22T16:06:00.459Z'
---

## Overview

An integer wraparound in an allocation size calculation in the BSON library's JSON parsing code can cause a buffer to be released while a following copy operation still writes through the stale pointer. On builds where sizes are 32 bits, an unauthenticated party able to supply a sufficiently large JSON input to an application that links the library may cause that application to terminate unexpectedly, resulting in denial of service.

## 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`