CVE-2026-34221 HIGH

CVE-2026-34221: MikroORM has Prototype Pollution in Utils.merge

Vendor Mikro-Orm
Product mikro-orm
Weakness CWE-1321
Published March 31, 2026
Last update March 31, 2026

CVSS base score

8.3/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality
Integrity

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:L/SA:L

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

March 31, 2026 CVE published
March 31, 2026 Record updated