CVE-2026-49451Public exploitNetwork attack vector

Process termination via circular schema reference recursion

Published Jun 30, 2026 · Updated Jun 30, 2026

Uncontrolled recursion in Microsoft OpenAPI.NET 2.0.0-preview.11 through 2.7.4 and 3.0.0 through 3.5.3 allows attackers to terminate processes. Reference resolution repeatedly follows mutually circular schema references without stopping before the thread exhausts its call stack. Exposure requires an application, CLI, developer tool, or service to parse an attacker-controlled JSON or YAML OpenAPI document in process; the bounded result is process termination.

CVSS severity7.5
High
EPSS probability1.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Uncontrolled recursion in Microsoft OpenAPI.NET 2.0.0-preview.11 through 2.7.4 and 3.0.0 through 3.5.3 allows attackers to terminate processes. Reference resolution repeatedly follows mutually circular schema references without stopping before the thread exhausts its call stack. Exposure requires an application, CLI, developer tool, or service to parse an attacker-controlled JSON or YAML OpenAPI document in process; the bounded result is process termination.

The record

CVE
CVE-2026-49451
Published
Jun 30, 2026
Updated
Jun 30, 2026
Vendor
Microsoft
Product
OpenAPI.NET
Classifications
CWE-674, CAPEC-230, CAPEC-231, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 30, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 30, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 2.0.0-preview11, < 2.7.5
  2. Affected versionversion=>= 3.0.0, < 3.5.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Microsoft · OpenAPI.NETversion=>= 2.0.0-preview11, < 2.7.5; version=>= 3.0.0, < 3.5.4

Published CVSS scores

7.5GitHub Advisory DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-674Uncontrolled Recursion
CAPEC-230Serialized Data with Nested Payloads
CAPEC-231Oversized Serialized Data Payloads
T1499Endpoint Denial of Service

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo