CVE-2026-72923
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…
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (1.20%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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 3.1
- 7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- EPSS
- 1.20% probability · 66th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-400
- Source
- security-advisories@github.com
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.