Vulnerability in Microsoft Openapi.net
CVE-2026-49451
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.
EPSS: 0.007 (49.3th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
Affected products
- Microsoft Openapi.net — versions >= 2.0.0-preview11, < 2.7.5, >= 3.0.0, < 3.5.4
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM)
Frequently asked questions
- What is CVE-2026-49451?
- CVE-2026-49451 is a high-severity vulnerability in Microsoft Openapi.net, classified under Uncontrolled Recursion. CVSS score: 7.5/10. Published 2026-06-30.
- How severe is CVE-2026-49451?
- High severity. CVSS v3 base score is 7.5 out of 10.