---
id: CVE-2026-34221
title: >-
  MikroORM is a TypeScript ORM for Node.js based on Data Mapper, Unit of Work
  and Identity Map patterns
summary: >-
  MikroORM is a TypeScript ORM for Node.js based on Data Mapper, Unit of Work
  and Identity Map patterns. Prior to versions 6.6.10 and 7.0.6, a prototype
  pollution vulnerability exists in the Utils.merge helper used internally by
  MikroORM w…
severity: critical
cvss: 9.1
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H'
cwe:
  - CWE-1321
vendor: mikro-orm
product: mikroorm
affected:
  - mikroorm < 6.6.10
  - 'mikroorm >= 7.0.0, < 7.0.6'
patched:
  - mikroorm 7.0.6
published: '2026-03-31'
updated: '2026-07-24'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-34221'
references:
  - url: >-
      https://github.com/mikro-orm/mikro-orm/security/advisories/GHSA-qpfv-44f3-qqx6
    label: security-advisories@github.com
tags:
  - nvd
epss: 0.00511
epssPercentile: 0.40972
ingestedAt: '2026-07-24T20:38:02.389Z'
---

## Overview

MikroORM is a TypeScript ORM for Node.js based on Data Mapper, Unit of Work and Identity Map patterns. Prior to versions 6.6.10 and 7.0.6, a prototype pollution vulnerability exists in the Utils.merge helper used internally by MikroORM when merging object structures. The function did not prevent special keys such as __proto__, constructor, or prototype, allowing attacker-controlled input to modify the JavaScript object prototype when merged. This issue has been patched in versions 6.6.10 and 7.0.6.

## Affected

- `mikroorm < 6.6.10`
- `mikroorm >= 7.0.0, < 7.0.6`

## Remediation

Upgrade past the affected range:

- `mikroorm 7.0.6`