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CVE-2026-27953

Vulnerability in ormar (CVE-2026-27953)

Summary

Vulnerability in ormar (CVE-2026-27953). Data can be tampered with by attackers. Exploitable via ormar. Mitigation: upgrade to 0.23.1 or later.

Original description

The description as published by the source.

Summary

A Pydantic validation bypass in ormar's model constructor allows any unauthenticated user to skip all field validation — type checks, constraints, @field_validator/@model_validator decorators, choices enforcement, and required-field checks — by injecting "__pk_only__": true into a JSON request body. The unvalidated data is subsequently persisted to the database. This affects the canonical usage pattern recommended in ormar's official documentation and examples.

A secondary __excluded__ parameter injection uses the same design pattern to selectively nullify arbitrary model fields during construction.

Details

Root cause: NewBaseModel.__init__ (ormar/models/newbasemodel.py, line 128) pops __pk_only__ directly from user-supplied **kwargs before any validation occurs:

# ormar/models/newbasemodel.py, lines 128-142
pk_only = kwargs.pop("__pk_only__", False)      # ← extracted from user kwargs
object.__setattr__(self, "__pk_only__", pk_only)

new_kwargs, through_tmp_dict = self._process_kwargs(kwargs)

if not pk_only:
    # Normal path: full Pydantic validation
    new_kwargs = self.serialize_nested_models_json_fields(new_kwargs)
    self.__pydantic_validator__.validate_python(
        new_kwargs, self_instance=self
    )
else:
    # Bypass path: NO validation at all
    fields_set = {self.ormar_config.pkname}
    values = new_kwargs
    obje…

Source: OSV.dev (Open Source Vulnerabilities) NVD GitHub Advisory OSV

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2026-27953 has been found in ormar.
Attackers can target a specific entry point like ormar over the network to misuse the product.
Data can be tampered with by attackers.
What to do: upgrade ormar to 0.23.1 or later.
If unsure, ask your IT team or search "ormar CVE-2026-27953" on the vendor's site.

CVE-2026-27953 (ormar) — CWE-20
Attack vector: remote (network-reachable) / no user interaction
Attack surface: ormar / __excluded__ / NewBaseModel.__init__ / __pk_only__
Patched: 0.23.1 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

A vulnerability (CWE-20) exists in ormar. Attackers reach the vulnerable code path via ormar.

📍 Affected scope

Check the vendor advisory for the affected versions of ormar. Attack surface: ormar / __excluded__ / NewBaseModel.__init__ / __pk_only__.

🔥 Severity

Severity: ?. Data can be tampered with by attackers.

🔧 How to fix

Update to 0.23.1.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'ormar' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposure identify 
    grep -r 'ormar' . | grep -v node_modules

    リポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で ormar を grep し、稼働しているサービス・バージョンを把握する。

  2. 2
    Apply patch patch 
    Upgrade ormar to 0.23.1

    ステージング環境で 0.23.1 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。

  3. 3
    Post-deployment verification verify 
    Confirm patched version is live in production

    パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Affected packages

PyPI ormar
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.23.1"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

References

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