NuGet · Microsoft.OpenAPI
Microsoft.OpenAPI: Circular schema references may terminate OpenAPI parsing
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.
>= 2.0.0-preview11, <= 2.7.4>= 3.0.0, <= 3.5.3Applications, CLIs, developer tools, or services that parse untrusted OpenAPI documents in-process may be terminated by a crafted OpenAPI document containing circular schema references.
The impact is availability/process termination only. This report does not claim remote code execution, authentication bypass, credential exposure, privilege escalation, data exposure, or Microsoft hosted service impact.
A standalone isolated-process harness confirmed repeatable process termination through public OpenAPI.NET reader APIs. The issue reproduces in the affected released NuGet packages and affects both JSON and YAML reader paths.
A separate Microsoft-owned local consumer, microsoft/kiota, also reproduces the termination through the kiota show --openapi <file> workflow. That workflow parses OpenAPI files in-process using Microsoft.OpenApi and Microsoft.OpenApi.YamlReader.
{
"openapi": "3.0.0",
"info": {
"title": "Test",
"version": "0.0.1"
},
"paths": {},
"components": {
"schemas": {
"A": {
"$ref": "#/components/schemas/B"
},
"B": {
"$ref": "#/components/schemas/A"
}
}
}
}
Users should upgrade to Microsoft.OpenApi 2.7.5 or 3.5.4, depending on the major version line they consume.
Applications that parse OpenAPI documents from untrusted sources should avoid parsing those documents in the primary application process when possible. Running parsing in an isolated process can reduce the blast radius of parser failures.
Is your project exposed to this? Stateward checks every dependency on every pull request and flags it only if your code actually reaches it.
Check my repoSources: CISA KEV (public domain), OSV.dev & GitHub Advisory Database (CC-BY-4.0), FIRST EPSS, NVD/CWE (public domain). Served live from the Stateward advisory database.