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.
Published · last modified .
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.
EPSS exploit prediction
EPSS: 0.012 (68.0th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 68th percentile — 68.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.012 · newest: 0.012 · change: 0.000
Affected products
- Microsoft Openapi.net — versions >= 2.0.0-preview11, < 2.7.5, >= 3.0.0, < 3.5.4
Weakness classification (CWE)
References
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.