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CVE-2026-49451

35
FAUCET Score

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.

First published: Jun 30, 2026Last modified: Jun 30, 2026

Impacted Technologies

VendorProductVersion(s)CPE
MicrosoftOpenAPI.NET
>= 2.0.0-preview11, < 2.7.5, >= 3.0.0, < 3.5.4CNA affected

CVSS Data

CVSS version used by this source: 3.1

7.5HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.69%
Probability of exploitation in next 30 days
EPSS Percentile
49.2%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0069 is in the 25th percentile among its peer group of 51,553 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (2)

nugetpatch availablevia ghsa
Product: Microsoft.OpenAPIFixed in: 3.5.4
nugetpatch availablevia ghsa
Product: Microsoft.OpenApiFixed in: 2.7.5

Vendor Advisories (1)

nugetGHSA-v5pm-xwqc-g5wchigh

Microsoft.OpenAPI: Circular schema references may terminate OpenAPI parsing

Jun 30, 2026

References

github.com / microsoft/OpenAPI.NET/security/advisories/GHSA-v5pm-xwqc-g5wc