How severe is CVE-2026-34221?

CVE-2026-34221 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability high.

Is CVE-2026-34221 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (30th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-34221?

CVE-2026-34221 affects Mikro-orm Mikroorm. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-34221?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

Does CVE-2026-34221 have an EU (EUVD) identifier?

Yes. CVE-2026-34221 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-17488.

When was CVE-2026-34221 published?

CVE-2026-34221 was published on 2026-03-31 and last updated on 2026-06-17.

CVE-2026-34221

CVE-2026-34221 is a critical-severity vulnerability in Mikro-orm Mikroorm with a CVSS 3.x base score of 9.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-1321.

Key facts

Severity: Critical (CVSS 3.x base score 9.1)
CVSS v4: 8.3
EPSS exploit prediction: 0% (30th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-17488
Weakness: CWE-1321
Affected product: Mikro-orm Mikroorm
Published: 2026-03-31
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2026-34221?: 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.
How severe is CVE-2026-34221?: CVE-2026-34221 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability high.
Is CVE-2026-34221 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (30th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-34221?: CVE-2026-34221 affects Mikro-orm Mikroorm. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-34221?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
Does CVE-2026-34221 have an EU (EUVD) identifier?: Yes. CVE-2026-34221 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-17488.
When was CVE-2026-34221 published?: CVE-2026-34221 was published on 2026-03-31 and last updated on 2026-06-17.

References

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

Affected products (1)

cpe:2.3:a:mikro-orm:mikroorm:*:*:*:*:*:node.js:*:*

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