CVE-2026-49451
HIGH 7.5The 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.
Severe if exploited (CVSS 7.5), but no known exploitation and low modeled probability. Patch on a normal cadence.
Exploitation likelihood
0.7%chance of exploitation in 30 days · 48th percentile
Impact if exploited
7.5CVSS 3.1 · HIGH
- ConfidentialityNone
- IntegrityNone
- AvailabilityHigh
What an attacker needs
- ✓Access: Reachable over the network — no local access needed
- ✓Privileges: No account or privileges required
- ✓User interaction: No user interaction needed
- ✓Complexity: No special conditions — reliably repeatable
✓ lowers the bar for an attacker · ⚠ raises it
Weakness (CWE)
- CWE-674
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H