CVE-2026-27953
ormar has a Pydantic Validation Bypass via Kwargs Injection in Model Constructor
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.
INFO
Published Date :
March 19, 2026, 9:17 p.m.
Last Modified :
March 19, 2026, 9:17 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-27953
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | HIGH | [email protected] |
Solution
- Update ormar to version 0.23.1 or later.
- Review data validation logic.
- Audit for persisted unvalidated data.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-27953.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-27953 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-27953
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-27953 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-27953 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
New CVE Received by [email protected]
Mar. 19, 2026
Action Type Old Value New Value Added 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. Added CVSS V3.1 AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:L Added CWE CWE-20 Added CWE CWE-915 Added Reference https://github.com/ormar-orm/ormar/blob/master/examples/fastapi_quick_start.py#L55 Added Reference https://github.com/ormar-orm/ormar/blob/master/ormar/fields/foreign_key.py#L41 Added Reference https://github.com/ormar-orm/ormar/blob/master/ormar/models/helpers/pydantic.py#L108 Added Reference https://github.com/ormar-orm/ormar/blob/master/ormar/models/model.py#L89 Added Reference https://github.com/ormar-orm/ormar/blob/master/ormar/models/newbasemodel.py#L128 Added Reference https://github.com/ormar-orm/ormar/blob/master/ormar/models/newbasemodel.py#L292 Added Reference https://github.com/ormar-orm/ormar/commit/7f22aa21a7614b993970345b392dabb0ccde0ab3 Added Reference https://github.com/ormar-orm/ormar/releases/tag/0.23.1 Added Reference https://github.com/ormar-orm/ormar/security/advisories/GHSA-f964-whrq-44h8