CVE-2026-34221

MikroORM has Prototype Pollution in Utils.merge

State: Published
Severity: 8.3 High
Published: Mar 31, 2026
Updated: Mar 31, 2026
Reserved: Mar 26, 2026

Description

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.

Scores

CVSS	Score	Vector	Source
4.0	8.3 High	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	GitHub_M

Weaknesses

CWE-1321 Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')

Affected Products

Product	Versions
mikro-ormmikro-orm	< 6.6.10Affected >= 7.0.0-rc.0, < 7.0.6Affected

References

https://github.com/mikro-orm/mikro-orm/security/advisories/GHSA-qpfv-44f3-qqx6

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