CVE-2026-72923
This vulnerability is fixed in Microsoft.OpenApi.Readers 1.6.30 and Microsoft.OpenApi.YamlReader 2.12.0 and 3.10.0.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (1.90%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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.
- CVSS 3.1
- 7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- EPSS
- 1.90% probability · 79th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-400
- Source
- security-advisories@github.com
EPSS 1.9% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- https://github.com/microsoft/OpenAPI.NET/commit/1f9aea9bdcbf4066b59ce33b3bd8f97ed9cb4766
- https://github.com/microsoft/OpenAPI.NET/commit/21793261d6860fb6e607b71fd95c0bd320724764
- https://github.com/microsoft/OpenAPI.NET/commit/4db9af07d112cdf45170b7a946f956ffe74fa14e
- https://github.com/microsoft/OpenAPI.NET/security/advisories/GHSA-7pxr-59rr-hqj2
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.