# CVE-2026-27953: ormar has a Pydantic Validation Bypass via Kwargs Injection in Model Constructor

> Attackers can bypass Pydantic validation in ormar ORM to inject unvalidated data or nullify fields, leading to privilege escalation and data integrity violations.

- **Severity:** High 7.1 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 19 Mar 2026
- **Updated:** 20 Mar 2026
- **Also known as:** DEBIAN-CVE-2026-27953, GHSA-f964-whrq-44h8, PYSEC-2026-2247, UBUNTU-CVE-2026-27953

## What is CVE-2026-27953?

CVE-2026-27953 is a high-severity vulnerability in ormar-orm ormar, published on 19 Mar 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official 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.

Weakness: CWE-915 (Improperly Controlled Modification of Dynamically-Determined Object Attributes), CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2026-27953?

3 open source packages ship an affected version, including ormar. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `ormar` | PyPI | All versions | 0.23.1 |
| `ormar` | PyPI | All versions | 0.23.1 |
| `ormar` | PyPI | All versions | 0.23.1 |

Products: Collerek Ormar.

## How do I fix CVE-2026-27953?

Upgrade ormar to 0.23.1 or later.

## Is CVE-2026-27953 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-27953 exists.

## Other vulnerabilities in ormar-orm ormar

- [CVE-2026-26198](https://insights.sbomify.com/CVE-2026-26198/): ormar is vulnerable to SQL Injection through aggregate functions min() and max() (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-27953 and fix it if it is affected.

What it is: CVE-2026-27953 is a high-severity vulnerability in ormar-orm ormar, published on 19 Mar 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-27953 exists.

Affected packages and fixed versions:
- ormar (PyPI): affected all versions; fixed in 0.23.1
- ormar (PyPI): affected all versions; fixed in 0.23.1
- ormar (PyPI): affected all versions; fixed in 0.23.1

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-27953/ (Markdown: https://insights.sbomify.com/CVE-2026-27953/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-27953
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-27953
- OSV: https://osv.dev/vulnerability/CVE-2026-27953

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-27953/
Summaries are generated and may contain mistakes; the official description above is the record.