CVE-2026-49451

Microsoft.OpenAPI: Circular schema references may terminate OpenAPI parsing

Published Jun 30, 2026 CVSS 3.1 · 7.5 High EPSS < 1% KEV · Not listed
Description
The OpenAPI.NET SDK contains a useful object model for OpenAPI documents in .NET along with common serializers to extract raw OpenAPI JSON and YAML documents from the model. From 2.0.0-preview11 until 2.7.5 and 3.5.4, a small OpenAPI document containing a circular schema reference can cause process termination through stack overflow in Microsoft.OpenApi. The issue affects OpenAPI document parsing through public OpenAPI.NET reader APIs and has been confirmed across both JSON and YAML reader paths. This vulnerability is fixed in 2.7.5 and 3.5.4.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-v5pm-xwqc-g5wc Microsoft.OpenAPI: Circular schema references may terminate OpenAPI parsing
History
Type Values Removed Values Added
First Time appeared Microsoft
Microsoft openapi.net
Vendors & Products Microsoft
Microsoft openapi.net
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description The OpenAPI.NET SDK contains a useful object model for OpenAPI documents in .NET along with common serializers to extract raw OpenAPI JSON and YAML documents from the model. From 2.0.0-preview11 until 2.7.5 and 3.5.4, a small OpenAPI document containing a circular schema reference can cause process termination through stack overflow in Microsoft.OpenApi. The issue affects OpenAPI document parsing through public OpenAPI.NET reader APIs and has been confirmed across both JSON and YAML reader paths. This vulnerability is fixed in 2.7.5 and 3.5.4.
Title Microsoft.OpenAPI: Circular schema references may terminate OpenAPI parsing
Weaknesses CWE-674
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Jun 30, 2026, 6:58 PM
Reserved
May 30, 2026, 2:43 AM
Status
Awaiting Analysis
Published
Jun 30, 2026, 5:16 PM
Modified
Oct 25, 2026, 9:10 PM