---
id: CVE-2026-114654
title: >-
  BSON output corruption via out-of-range binary subtype bypassing UUID and
  OldBinary guards
summary: >-
  A numeric-type conversion flaw in the BSON handling library of the MongoDB C#
  Driver allows an out-of-range binary subtype value supplied through untrusted
  textual input to bypass the library's binary-element integrity checks. When
  such …
severity: medium
cvss: 6.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L'
cvssSource: cna
cwe:
  - CWE-681
vendor: MongoDB
product: C# Driver
affected:
  - c_driver >= 2.0.0 < 3.13.0
published: '2026-10-22'
updated: '2026-10-22'
sourceUpdated: '2026-10-22T21:25:37.785Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-114654'
references:
  - url: 'https://jira.mongodb.org/browse/CSHARP-6166'
  - url: 'https://github.com/mongodb/mongo-csharp-driver/releases/tag/v3.13.0'
  - url: >-
      https://github.com/mongodb/mongo-csharp-driver/security/advisories/GHSA-5h2q-6c9r-7x25
tags:
  - cve.org
ingestedAt: '2026-10-22T22:00:50.448Z'
---

## Overview

A numeric-type conversion flaw in the BSON handling library of the MongoDB C# Driver allows an out-of-range binary subtype value supplied through untrusted textual input to bypass the library's binary-element integrity checks. When such a value is later encoded, it is narrowed to a smaller wire representation, producing binary elements that misdeclare their type or length. An unauthenticated party able to supply text parsed by an affected application can cause it to emit and persist malformed binary data, which subsequent readers either reject with an error or silently interpret as shorter than the data that was validated.

## Affected

- `c_driver >= 2.0.0 < 3.13.0`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.