CVE-2026-27953
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.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (1.19%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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
- 9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 1.19% probability · 66th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-20, CWE-915
- Affected
- collerek/ormar
- Source
- security-advisories@github.com
References
- https://github.com/ormar-orm/ormar/blob/master/examples/fastapi_quick_start.py#L55Patch
- https://github.com/ormar-orm/ormar/blob/master/ormar/fields/foreign_key.py#L41Patch
- https://github.com/ormar-orm/ormar/blob/master/ormar/models/helpers/pydantic.py#L108Patch
- https://github.com/ormar-orm/ormar/blob/master/ormar/models/model.py#L89Patch
- https://github.com/ormar-orm/ormar/blob/master/ormar/models/newbasemodel.py#L128Patch
- https://github.com/ormar-orm/ormar/blob/master/ormar/models/newbasemodel.py#L292Patch
- https://github.com/ormar-orm/ormar/commit/7f22aa21a7614b993970345b392dabb0ccde0ab3Patch
- https://github.com/ormar-orm/ormar/releases/tag/0.23.1Product, Release Notes
- https://github.com/ormar-orm/ormar/security/advisories/GHSA-f964-whrq-44h8Exploit, Mitigation, Vendor Advisory
- https://github.com/ormar-orm/ormar/security/advisories/GHSA-f964-whrq-44h8Exploit, Mitigation, Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.