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CVE-2026-72923— Microsoft.OpenApi.YamlReader/Readers vulnerable to denial of service via YAML alias expansion

Quick assessment

Affected
Microsoft OpenApi.YamlReader
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

在 Microsoft.OpenApi.YamlReader 中，受影响版本包括： 2.0.0-preview.11 至 2.12.0 3.0.0 至 3.10.0 以及在 Microsoft.OpenApi.Readers 1.6.30 之前的版本中，存在一个安全漏洞：当通过公共 YAML 读取器 API 解析包含嵌套锚点（anchors）和别名（aliases）的小型 YAML OpenAPI 文档时，可能导致资源消耗失控。 具体机理如下： YAML 通过 SharpYaml 解析器进行解析，其中别名被表示为有

CVSS 7.5 · High

Possible ATT&CK Techniques 1 AI

T1499 · Endpoint Denial of Service

Affected Version Matrix 3

VendorProduct Version RangeStatus
Microsoft OpenApi.Readers < 1.6.30 affected
Microsoft OpenApi.YamlReader 2.0.0-preview.11< 2.12.0 affected
3.0.0< 3.10.0 affected
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I. Basic Information for CVE-2026-72923

Vulnerability Information
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Vulnerability Title
Microsoft.OpenApi.YamlReader/Readers vulnerable to denial of service via YAML alias expansion
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
未加控制的资源消耗(资源穷尽)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
Microsoft OpenApi.YamlReader 2.0.0-preview.11 ~ 2.12.0 -
Microsoft OpenApi.Readers 0 ~ 1.6.30 -

II. Public POCs for CVE-2026-72923

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III. Intelligence Information for CVE-2026-72923

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Vendor Advisories for CVE-2026-72923 (1)

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Showing top 20 of 966 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same vendor: Microsoft
Same weakness: CWE-400

V. Comments for CVE-2026-72923

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