---
id: CVE-2026-81521
title: >-
  The MongoDB Go Driver's client-level bulk write operation may accept a
  caller-supplied database name containing a reserved separator character
  without escaping it before the name is used to build the target namespace for
  the operation
summary: >-
  The MongoDB Go Driver's client-level bulk write operation may accept a
  caller-supplied database name containing a reserved separator character
  without escaping it before the name is used to build the target namespace for
  the operation. A…
severity: medium
cvss: 6.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N'
cwe:
  - CWE-99
vendor: mongodb
product: go_driver
affected:
  - 'go_driver >= 2.1.0, < 2.8.2'
patched:
  - go_driver 2.8.2
published: '2026-08-27'
updated: '2026-09-29'
sourceUpdated: '2026-09-29T19:17:28.347'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-81521'
references:
  - url: 'https://jira.mongodb.org/browse/GODRIVER-4075'
    label: cna@mongodb.com
  - url: 'https://pkg.go.dev/go.mongodb.org/mongo-driver/v2@v2.8.2'
    label: cna@mongodb.com
tags:
  - nvd
epss: 0.00349
epssPercentile: 0.25941
ingestedAt: '2026-09-29T19:44:04.116Z'
---

## Overview

The MongoDB Go Driver's client-level bulk write operation may accept a caller-supplied database name containing a reserved separator character without escaping it before the name is used to build the target namespace for the operation. An application that passes untrusted input as a database name could therefore have the write directed at a database and collection other than the ones it intended. Only the Client.BulkWrite API is affected.

## Affected

- `go_driver >= 2.1.0, < 2.8.2`

## Remediation

Upgrade past the affected range:

- `go_driver 2.8.2`