CVE-2026-72923
Received
Received - Intake
YAML Parsing DoS in Microsoft OpenAPI Libraries
Vulnerability report for CVE-2026-72923, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-09-08
Last updated on: 2026-09-08
Assigner: GitHub, Inc.
Description
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.
CVSS Scores
EPSS Scores
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| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| microsoft | openapi_yamlreader | From 2.0.0-preview.11 (inc) to 2.12.0 (inc) |
| microsoft | openapi_yamlreader | From 3.0.0 (inc) to 3.10.0 (inc) |
| microsoft | openapi_readers | to 1.6.30 (exc) |
| microsoft | openapi_yamlreader | 2.12.0 |
| microsoft | openapi_yamlreader | 3.10.0 |
| microsoft | openapi_readers | 1.6.30 |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-400 | The product does not properly control the allocation and maintenance of a limited resource. |
