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.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
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.
Which versions are affected by CVE-2026-27953?
3 open source packages ship an affected version, including ormar. It affects 1 product.
| Package | 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 include 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
Sources
Also known as DEBIAN-CVE-2026-27953, GHSA-f964-whrq-44h8, PYSEC-2026-2247, UBUNTU-CVE-2026-27953.