CVE-2026-34221CWE-1321

MikroORM has Prototype Pollution in Utils.merge

High · published March 31, 2026

CVSS v4.0
8.3
EPSS
1%
Percentile
42.7
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v4.0
8.3 · HIGH
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
EPSS
0.00511 · 42.7th percentile
Weakness
CWE-1321 · Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
Published
2026-03-31T15:17Z
EPSS history
Timeline
  • 31 MAR 15:17Z
    MikroORM has Prototype Pollution in Utils.merge
    cvelistv5