Exploitation ongoing with high activity in latest observed window (1 mentions)
Recommended action window: Immediate (within 24h)
NVD 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.
Priority
LOW
Exploitation
ACTIVE
PoC
NONE
Patch
NONE
Momentum
STABLE
| Date | Total | Labels |
|---|
| 2026-06-30 | 2 | General2 |
| 2026-07-01 | 1 | Active Exploitation1 |
Our CTI team identified a lot of activities targeting Microsoft http://OpenAPI.NET (CVE-2026-49451) https://vuldb.com/vuln/374875/cti
Post summary
The CTI team reports that CVE‑2026‑49451 is being actively targeted, but provides no PoC, exploit code, patch information, or technical details.
🚨*CVE* CVE-2026-49451 The http://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… https://www.cve.org/CVERecord?id=CVE-2026-49451 ----- Traducción: CVE-20… http://infoflow.cloud`
Post summary
The text only mentions CVE‑2026‑49451 and links to the CVE record, without providing additional technical or exploitation details.
CVE-2026-49451 The http://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… https://www.cve.org/CVERecord?id=CVE-2026-49451
Post summary
The text references CVE-2026-49451 and links to its CVE record but provides no substantive detail on the vulnerability, exploit, patch, or activity.