mikro-orm MikroORM up to 6.6.9/7.0.5 Javascript Object prototype pollution

Summaryinfo

A vulnerability classified as critical was found in mikro-orm MikroORM up to 6.6.9/7.0.5. The impacted element is an unknown function of the component Javascript Object Handler. The manipulation results in prototype pollution. This vulnerability was named CVE-2026-34221. The attack may be performed from remote. There is no available exploit. Upgrading the affected component is advised.

Detailsinfo

A vulnerability classified as critical has been found in mikro-orm MikroORM up to 6.6.9/7.0.5. Affected is an unknown function of the component Javascript Object Handler. The manipulation with an unknown input leads to a prototype pollution vulnerability. CWE is classifying the issue as CWE-1321. The product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype. This is going to have an impact on integrity, and availability. CVE summarizes:

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 advisory is available at github.com. This vulnerability is traded as CVE-2026-34221 since 03/26/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. The technical details are unknown and an exploit is not available. This vulnerability is assigned to T1059 by the MITRE ATT&CK project.

Upgrading to version 6.6.10 or 7.0.6 eliminates this vulnerability.

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Productinfo

Vendor

• mikro-orm

Name

• MikroORM

Version

• 6.6.0
• 6.6.1
• 6.6.2
• 6.6.3
• 6.6.4
• 6.6.5
• 6.6.6
• 6.6.7
• 6.6.8
• 6.6.9
• 7.0.0
• 7.0.1
• 7.0.2
• 7.0.3
• 7.0.4
• 7.0.5

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