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Vulnerability record · CVE-2026-27953 · published 19 March 2026

CVE-2026-27953: Collerek ormar improper input validation vulnerability

CCollerek · Ormar

ormar is a async mini ORM for Python. Versions 0.23.0 and below are vulnerable to Pydantic validation bypass through the model constructor, allowing any unauthenticated user to skip all field validation by injecting "__pk_only__": true into a JSON request body. By injecting "__pk_only__": true into a JSON request body, an unauthenticated attacker can skip all field validation and persist unvalidated data directly to the database. A secondary __excluded__ parameter injection uses the same pattern to selectively nullify arbitrary model fields (e.g., email or role) during construction. This affects ormar's canonical FastAPI integration pattern recommended in its official documentation, enabling privilege escalation, data integrity violations, and business logic bypass in any application using ormar.Model directly as a request body parameter. This issue has been fixed in version 0.23.1.

9.8 CVSS 3.1 Critical EPSS 0.91% · top 41.7% CWE-20 · Improper input validationCWE-915 · Mass assignment
9.8CVSS 3.1 base score
0.91%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
10References, 2 tagged exploit
17 Jun 2026Last modified by NVD

Description

ormar is a async mini ORM for Python. Versions 0.23.0 and below are vulnerable to Pydantic validation bypass through the model constructor, allowing any unauthenticated user to skip all field validation by injecting "__pk_only__": true into a JSON request body. By injecting "__pk_only__": true into a JSON request body, an unauthenticated attacker can skip all field validation and persist unvalidated data directly to the database. A secondary __excluded__ parameter injection uses the same pattern to selectively nullify arbitrary model fields (e.g., email or role) during construction. This affects ormar's canonical FastAPI integration pattern recommended in its official documentation, enabling privilege escalation, data integrity violations, and business logic bypass in any application using ormar.Model directly as a request body parameter. This issue has been fixed in version 0.23.1.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/ormar-orm/ormar/blob/master/examples/fastapi_quick_start.py#L55 Patch
https://github.com/ormar-orm/ormar/blob/master/ormar/fields/foreign_key.py#L41 Patch
https://github.com/ormar-orm/ormar/blob/master/ormar/models/helpers/pydantic.py#L108 Patch
https://github.com/ormar-orm/ormar/blob/master/ormar/models/model.py#L89 Patch
https://github.com/ormar-orm/ormar/blob/master/ormar/models/newbasemodel.py#L128 Patch
https://github.com/ormar-orm/ormar/blob/master/ormar/models/newbasemodel.py#L292 Patch
https://github.com/ormar-orm/ormar/commit/7f22aa21a7614b993970345b392dabb0ccde0ab3 Patch
https://github.com/ormar-orm/ormar/releases/tag/0.23.1 ProductRelease Notes
https://github.com/ormar-orm/ormar/security/advisories/GHSA-f964-whrq-44h8 ExploitMitigationVendor Advisory
https://github.com/ormar-orm/ormar/security/advisories/GHSA-f964-whrq-44h8 ExploitMitigationVendor Advisory

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Source: NIST National Vulnerability Database (record CVE-2026-27953), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.