CVE-2026-49451

HIGH

Microsoft.OpenAPI: Circular schema references may terminate OpenAPI parsing

Title source: cna
STIX 2.1

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.

References (1)

Core 1
Core References

Scores

CVSS v3 7.5
EPSS 0.0069
EPSS Percentile 48.7%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CISA SSVC

Vulnrichment
Exploitation poc
Automatable yes
Technical Impact partial

Details

CWE
CWE-674
Status published
Products (4)
microsoft/OpenAPI.NET >= 2.0.0-preview11, < 2.7.5
microsoft/OpenAPI.NET >= 3.0.0, < 3.5.4
nuget/Microsoft.OpenApi 2.0.0-preview.11 - 2.7.5NuGet
nuget/Microsoft.OpenApi 3.0.0 - 3.5.4NuGet
Published Jun 30, 2026
Tracked Since Jun 30, 2026