# Microsoft.OpenApi.YamlReader vulnerable to denial of service via YAML alias expansion

Advisory record · `GHSA-7pxr-59rr-hqj2`

- **Identifiers:** `GHSA-7pxr-59rr-hqj2` · `CVE-2026-72923`
- **State:** Confirmed
- **Severity:** CVSS 7.5 High
- **Critical:** No
- **Weakness (CWE):** [CWE-400](https://cwe.mitre.org/data/definitions/400.html) · [CWE-770](https://cwe.mitre.org/data/definitions/770.html)
- **Tags:** [Denial of service](https://agentprime.io/advisories/tag/dos.md)
- **Published:** 14 Oct 2026
- **Updated:** 14 Oct 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 14 Oct 2026, 20:11 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `Microsoft.OpenApi.YamlReader` (NuGet): affected `>=3.0.0, <3.10.0 || >=2.0.0-preview.11, <2.12.0`; fixed in `3.10.0`, `2.12.0`
- `Microsoft.OpenApi.Readers` (NuGet): affected `<1.6.30`; fixed in `1.6.30`

## Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

## Severity and exploitation

- 7.5 High, CVSS 3.1: `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`, from CNA (GitHub_M)

- **CISA KEV:** Not listed.
- **EPSS:** 0.018, the 79th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 31 Oct 2026, 15:21 UTC: First seen by agentprime
- 31 Oct 2026, 15:21 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-7pxr-59rr-hqj2)

## Sources

- [GitHub Advisory Database: GHSA-7pxr-59rr-hqj2](https://github.com/advisories/GHSA-7pxr-59rr-hqj2)
- [OSV: GHSA-7pxr-59rr-hqj2](https://osv.dev/vulnerability/GHSA-7pxr-59rr-hqj2)
- <https://github.com/microsoft/OpenAPI.NET/security/advisories/GHSA-7pxr-59rr-hqj2>
- <https://nvd.nist.gov/vuln/detail/CVE-2026-72923>
- <https://github.com/microsoft/OpenAPI.NET/pull/3000>
- <https://github.com/microsoft/OpenAPI.NET/pull/3005>
- <https://github.com/microsoft/OpenAPI.NET/pull/3020>
- <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>
- <https://github.com/microsoft/OpenAPI.NET/releases/tag/v1.6.30>
- <https://github.com/microsoft/OpenAPI.NET/releases/tag/v2.12.0>
- <https://github.com/microsoft/OpenAPI.NET/releases/tag/v3.10.0>

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.

## Check whether this affects you

A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: <https://agentprime.io/mcp.md>
- In a browser: <https://agentprime.io/check/> reads your lockfile in the browser, never uploading it.
- Whether it touches your code, with file and line: the Claude Code plugin, <https://agentprime.io/plugin.md>
- As JSON: <https://api.agentprime.io/v1/advisories/GHSA-7pxr-59rr-hqj2>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

---

The web page: <https://agentprime.io/advisories/GHSA-7pxr-59rr-hqj2/>. Everything for agents: <https://agentprime.io/llms.txt>.