AIKIDO-2026-423403
Microsoft.OpenApi.YamlReader is vulnerable to Uncontrolled Resource Consumption
53
Medium Risk
This Affects:
Microsoft.OpenApi.YamlReaderTL;DR
The YAML reader expands YAML anchors and aliases without bounding nesting depth or the number of materialized nodes. A small crafted YAML OpenAPI document that uses recursive alias expansion (a billion laughs payload) forces YamlConverter to allocate an exponentially large node graph. Parsing such a document through the public OpenAPI reader APIs exhausts process memory and can terminate the host process. The fix enforces maximum nesting-depth and node-count limits and surfaces a diagnostic error instead of continuing expansion.
Who does this affect?
You are affected if you are using a version that falls within the vulnerable range and your application parses untrusted or externally influenced YAML OpenAPI documents through the reader APIs.
Background info
Microsoft.OpenApi.YamlReader is vulnerable to Uncontrolled Resource Consumption in versions 2.0.0 - 2.11.0 and 3.0.0 - 3.9.0.
How to fix this
Upgrade the Microsoft.OpenApi.YamlReader library to the patch version.
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SOC 2Compliant
ISO 27001Compliant