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. In Microsoft.OpenApi.Readers versions before 1.6.30 and Microsoft.OpenApi.YamlReader from 2.0.0-preview.11 through 2.11.0 and 3.0.0 through 3.9.0, parsing a YAML OpenAPI document with nested anchors and aliases can consume uncontrolled memory. SharpYaml represents aliases as shared nodes in a small directed acyclic graph, but conversion to independent OpenAPI or System.Text.Json.Nodes.JsonNode trees duplicates every aliased path; without a node-count or nesting-depth limit, N nested anchors referenced k times can require k^N materialized nodes and terminate the process through an out-of-memory condition. The fixed readers bound materialization to 5,000,000 nodes and a nesting depth of 64 by default and report an OpenApiDiagnostic error when a limit is exceeded. This vulnerability is fixed in Microsoft.OpenApi.Readers 1.6.30 and Microsoft.OpenApi.YamlReader 2.12.0 and 3.10.0.
Analysis
Analysis and contextual insights are available on OpenCVE Cloud.
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||||||||
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| microsoft | OpenAPI.NET | affected |
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| Vendor | Product | Confidence | Versions | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Microsoft | Openapi.readers | 100% |
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| Microsoft | Openapi.yamlreader | 100% |
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Remediation
No solution or workaround provided in the CVE record.
Additional remediation guidance may be available on OpenCVE Cloud.
Tracking
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Advisories
| Source | ID | Title |
|---|---|---|
 Github GHSA |
GHSA-7pxr-59rr-hqj2 | Microsoft.OpenApi.YamlReader vulnerable to denial of service via YAML alias expansion |
References
History
Wed, 14 Oct 2026 20:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In Microsoft.OpenApi.YamlReader from 2.0.0-preview.11 until 2.12.0 and from 3.0.0 until 3.10.0, and in Microsoft.OpenApi.Readers prior to 1.6.30, a small YAML OpenAPI document containing nested anchors and aliases can cause uncontrolled resource consumption when parsed through the public YAML reader APIs. YAML is parsed through SharpYaml, which represents aliases as shared nodes in a directed acyclic graph, so the parsed YAML graph stays small, but converting that graph to System.Text.Json.Nodes.JsonNode requires every alias to be materialized as an independent node because a JsonNode cannot be attached to multiple parents. Without a bound on that conversion work, a document with N nested anchors each referenced k times can require k^N materialized JSON nodes, leading to excessive memory allocation and process termination through out-of-memory conditions, a billion laughs style denial of service. The patched versions bound the YAML-to-JSON conversion by node count and nesting depth and report an OpenApiDiagnostic error instead of expanding without limit. This vulnerability is fixed in Microsoft.OpenApi.YamlReader 2.12.0 and 3.10.0, and Microsoft.OpenApi.Readers 1.6.30. | 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. In Microsoft.OpenApi.Readers versions before 1.6.30 and Microsoft.OpenApi.YamlReader from 2.0.0-preview.11 through 2.11.0 and 3.0.0 through 3.9.0, parsing a YAML OpenAPI document with nested anchors and aliases can consume uncontrolled memory. SharpYaml represents aliases as shared nodes in a small directed acyclic graph, but conversion to independent OpenAPI or System.Text.Json.Nodes.JsonNode trees duplicates every aliased path; without a node-count or nesting-depth limit, N nested anchors referenced k times can require k^N materialized nodes and terminate the process through an out-of-memory condition. The fixed readers bound materialization to 5,000,000 nodes and a nesting depth of 64 by default and report an OpenApiDiagnostic error when a limit is exceeded. This vulnerability is fixed in Microsoft.OpenApi.Readers 1.6.30 and Microsoft.OpenApi.YamlReader 2.12.0 and 3.10.0. |
| Title | Microsoft.OpenApi.YamlReader/Readers vulnerable to denial of service via YAML alias expansion | Microsoft.OpenApi.YamlReader vulnerable to denial of service via YAML alias expansion |
| References |
|
Tue, 08 Sep 2026 21:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Microsoft
Microsoft openapi.readers Microsoft openapi.yamlreader |
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| Vendors & Products |
Microsoft
Microsoft openapi.readers Microsoft openapi.yamlreader |
Tue, 08 Sep 2026 18:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Metrics |
ssvc
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Tue, 08 Sep 2026 18:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In Microsoft.OpenApi.YamlReader from 2.0.0-preview.11 until 2.12.2 and from 3.0.0 until 3.10.2, and in Microsoft.OpenApi.Readers prior to 1.6.31, a small YAML OpenAPI document containing nested anchors and aliases can cause uncontrolled resource consumption when parsed through the public YAML reader APIs. YAML is parsed through SharpYaml, which represents aliases as shared nodes in a directed acyclic graph, so the parsed YAML graph stays small, but converting that graph to System.Text.Json.Nodes.JsonNode requires every alias to be materialized as an independent node because a JsonNode cannot be attached to multiple parents. Without a bound on that conversion work, a document with N nested anchors each referenced k times can require k^N materialized JSON nodes, leading to excessive memory allocation and process termination through out-of-memory conditions, a billion laughs style denial of service. The patched versions bound the YAML-to-JSON conversion by node count and nesting depth and report an OpenApiDiagnostic error instead of expanding without limit. This vulnerability is fixed in Microsoft.OpenApi.YamlReader 2.12.2 and 3.10.2, and Microsoft.OpenApi.Readers 1.6.31. | In Microsoft.OpenApi.YamlReader from 2.0.0-preview.11 until 2.12.0 and from 3.0.0 until 3.10.0, and in Microsoft.OpenApi.Readers prior to 1.6.30, a small YAML OpenAPI document containing nested anchors and aliases can cause uncontrolled resource consumption when parsed through the public YAML reader APIs. YAML is parsed through SharpYaml, which represents aliases as shared nodes in a directed acyclic graph, so the parsed YAML graph stays small, but converting that graph to System.Text.Json.Nodes.JsonNode requires every alias to be materialized as an independent node because a JsonNode cannot be attached to multiple parents. Without a bound on that conversion work, a document with N nested anchors each referenced k times can require k^N materialized JSON nodes, leading to excessive memory allocation and process termination through out-of-memory conditions, a billion laughs style denial of service. The patched versions bound the YAML-to-JSON conversion by node count and nesting depth and report an OpenApiDiagnostic error instead of expanding without limit. This vulnerability is fixed in Microsoft.OpenApi.YamlReader 2.12.0 and 3.10.0, and Microsoft.OpenApi.Readers 1.6.30. |
Tue, 08 Sep 2026 17:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In Microsoft.OpenApi.YamlReader from 2.0.0-preview.11 until 2.12.2 and from 3.0.0 until 3.10.2, and in Microsoft.OpenApi.Readers prior to 1.6.31, a small YAML OpenAPI document containing nested anchors and aliases can cause uncontrolled resource consumption when parsed through the public YAML reader APIs. YAML is parsed through SharpYaml, which represents aliases as shared nodes in a directed acyclic graph, so the parsed YAML graph stays small, but converting that graph to System.Text.Json.Nodes.JsonNode requires every alias to be materialized as an independent node because a JsonNode cannot be attached to multiple parents. Without a bound on that conversion work, a document with N nested anchors each referenced k times can require k^N materialized JSON nodes, leading to excessive memory allocation and process termination through out-of-memory conditions, a billion laughs style denial of service. The patched versions bound the YAML-to-JSON conversion by node count and nesting depth and report an OpenApiDiagnostic error instead of expanding without limit. This vulnerability is fixed in Microsoft.OpenApi.YamlReader 2.12.2 and 3.10.2, and Microsoft.OpenApi.Readers 1.6.31. | |
| Title | Microsoft.OpenApi.YamlReader/Readers vulnerable to denial of service via YAML alias expansion | |
| Weaknesses | CWE-400 | |
| References |
| |
| Metrics |
cvssV3_1
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MITRE
Status: PUBLISHED
Assigner: GitHub_M
Published:
Updated: 2026-10-14T20:08:53.059Z
Reserved: 2026-08-10T17:57:26.144Z
Link: CVE-2026-72923
Vulnrichment
Updated: 2026-09-08T17:37:08.978Z
NVD
Status : Deferred
Published: 2026-09-08T18:20:16.310
Modified: 2026-10-14T21:17:39.323
Link: CVE-2026-72923
Redhat
No data.
OpenCVE Enrichment
Updated: 2026-09-10T00:45:07Z
Weaknesses