---
id: CVE-2026-88035
title: >-
  A size check in the client-side authentication path of the MongoDB C Driver
  can wrap around, so an unusually large user-name value is accepted and copied
  past the end of a small buffer
summary: >-
  A size check in the client-side authentication path of the MongoDB C Driver
  can wrap around, so an unusually large user-name value is accepted and copied
  past the end of a small buffer. A party able to set the driver's connection
  setting…
severity: medium
cvss: 4.7
cvssVector: 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-190
vendor: mongodb
product: c_driver
affected:
  - 'c_driver >= 1.10.0, < 1.30.10'
  - 'c_driver >= 2.2.0, < 2.5.3'
patched:
  - c_driver 2.5.3
published: '2026-09-10'
updated: '2026-09-16'
sourceUpdated: '2026-09-16T18:08:46.303'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-88035'
references:
  - url: 'https://jira.mongodb.org/browse/CDRIVER-6416'
    label: cna@mongodb.com
tags:
  - nvd
  - cve.org
epss: 0.00141
epssPercentile: 0.0279
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-10T18:29:41.143877Z'
ingestedAt: '2026-09-13T19:09:30.561Z'
---

## Overview

A size check in the client-side authentication path of the MongoDB C Driver can wrap around, so an unusually large user-name value is accepted and copied past the end of a small buffer. A party able to set the driver's connection settings may cause the application that embeds the driver to terminate unexpectedly. Reaching this code requires a build in which the optional external SASL authentication backend is present and a connection configured to use it.

## Affected

- `c_driver >= 1.10.0, < 1.30.10`
- `c_driver >= 2.2.0, < 2.5.3`

## Remediation

Upgrade past the affected range:

- `c_driver 2.5.3`