CVE-2026-27953

CRITICALNVD 9.89.8
EchelonGraph scoreLOW confidence

This critical-severity CVE scores 9.8 under NVD CVSS v3. EPSS exploit-prediction score not yet available (the EPSS model rescores nightly; freshly-published CVEs typically appear within 48 hours). GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: nvd
9.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: —CVSS: 9.8Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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 v3
9.8
EG Score
9.8(low)
EG Risk
49(Track)
EG Risk 49/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity98% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
—
EPSS %ILE
—
KEV
Not listed

Published

March 19, 2026

Last Modified

June 17, 2026

Advisory Details (9)

Auto-updated Jul 27, 2026
🔬 Proof of concept available. Patch available. Sources: github_commit, github_release, github.
github Patch Available🟡 PoC Available

Pydantic Validation Bypass via __pk_only__ and __excluded__ Kwargs Injection in Model Constructor · Advisory · ormar-orm/ormar · GitHub

https://github.com/ormar-orm/ormar/security/advisories/GHSA-f964-whrq-44h8
github_release Patch Available

Fix high vulnerability with kwargs injection

Patch available: ormar-orm/ormar 0.23.1

https://github.com/ormar-orm/ormar/releases/tag/0.23.1
github_commit Patch Available

commit 7f22aa21a761 (ormar-orm/ormar)

Patch available: ormar-orm/ormar 0.23.1 (contains commit 7f22aa21a761)

https://github.com/ormar-orm/ormar/commit/7f22aa21a7614b993970345b392dabb0ccde0ab3
generic

ormar/ormar/models/newbasemodel.py at master · ormar-orm/ormar · GitHub

https://github.com/ormar-orm/ormar/blob/master/ormar/models/newbasemodel.py#L292
generic

ormar/ormar/models/newbasemodel.py at master · ormar-orm/ormar · GitHub

https://github.com/ormar-orm/ormar/blob/master/ormar/models/newbasemodel.py#L128
generic

ormar/ormar/models/model.py at master · ormar-orm/ormar · GitHub

https://github.com/ormar-orm/ormar/blob/master/ormar/models/model.py#L89
generic

ormar/ormar/models/helpers/pydantic.py at master · ormar-orm/ormar · GitHub

https://github.com/ormar-orm/ormar/blob/master/ormar/models/helpers/pydantic.py#L108
generic

ormar/ormar/fields/foreign_key.py at master · ormar-orm/ormar · GitHub

https://github.com/ormar-orm/ormar/blob/master/ormar/fields/foreign_key.py#L41
generic

ormar/examples/fastapi_quick_start.py at master · ormar-orm/ormar · GitHub

https://github.com/ormar-orm/ormar/blob/master/examples/fastapi_quick_start.py#L55

Weakness Classification(2)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 1× in last 7d / 1× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-27 14:38 UTCEG score recompute

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Frequently asked(4)

What is CVE-2026-27953?
CVE-2026-27953 is a critical vulnerability published on March 19, 2026. 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 "pkonly": true into a JSON request body. By injecting "pkonly": true into a JSON…
When was CVE-2026-27953 disclosed?
CVE-2026-27953 was first published in the National Vulnerability Database on March 19, 2026, with the most recent update on June 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
What is the CVSS score of CVE-2026-27953?
CVE-2026-27953 has a CVSS v3 base score of 9.8 (NVD). The EG score is currently aggregating — additional source signals are being incorporated as they become available..
How do I remediate CVE-2026-27953?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-27953, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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