CVE-2026-49451Microsoft.OpenAPI: Circular schema references may terminate OpenAPI parsing
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No exploitation reported and no EPSS estimate yet.
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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.
- CVSS
- 7.5 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Weakness (CWE)
- CWE-674
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- GitHub_M
- NVD analysis
- Awaiting Analysis
- Record last updated
- Jun 30, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
microsoft OpenAPI.NET microsoft:openapi.net (from the name) | from 2.0.0-preview11, < 2.7.5; from 3.0.0, < 3.5.4 | CNA record |
References
- https://github.com/microsoft/OpenAPI.NET/security/advisories/GHSA-v5pm-xwqc-g5wcx-refsource-confirm
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.