# Microsoft Security Advisory CVE-2026-69304 – ASP.NET Core Denial of Service Vulnerability

Advisory record · `GHSA-8cp2-47hg-mfgh`

- **Identifiers:** `GHSA-8cp2-47hg-mfgh` · `BIT-aspnet-core-2026-69304` · `BIT-dotnet-2026-69304` · `BIT-dotnet-sdk-2026-69304` · `CVE-2026-69304`
- **State:** Confirmed
- **Severity:** CVSS 5.9 Medium
- **Critical:** No
- **Weakness (CWE):** [CWE-409](https://cwe.mitre.org/data/definitions/409.html)
- **Tags:** [CWE-409](https://agentprime.io/advisories/tag/cwe-409.md)
- **Published:** 9 Sept 2026
- **Updated:** 1 Oct 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 9 Sept 2026, 16:04 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `Microsoft.AspNetCore.Server.IISIntegration` (NuGet): affected `>=11.0.0-preview.1, <11.0.0-rc.1 || >=8.0.0, <8.0.31 || >=9.0.0, <9.0.20 || >=10.0.0, <10.0.12`; fixed in `11.0.0-rc.1`, `8.0.31`, `9.0.20`, `10.0.12`

## 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

- 5.9 Medium, CVSS 3.1: `CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C`, from CNA (microsoft)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0086, the 58th percentile, on 6 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 8 Sept 2026, 17:17 UTC: [Confirmed by the CVE List](https://www.cve.org/CVERecord?id=CVE-2026-69304)
- 31 Oct 2026, 15:21 UTC: First seen by agentprime
- 31 Oct 2026, 15:21 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-8cp2-47hg-mfgh)

## Sources

- [GitHub Advisory Database: GHSA-8cp2-47hg-mfgh](https://github.com/advisories/GHSA-8cp2-47hg-mfgh)
- [OSV: GHSA-8cp2-47hg-mfgh](https://osv.dev/vulnerability/GHSA-8cp2-47hg-mfgh)
- <https://github.com/dotnet/aspnetcore/security/advisories/GHSA-8cp2-47hg-mfgh>
- <https://nvd.nist.gov/vuln/detail/CVE-2026-69304>
- <https://github.com/dotnet/aspnetcore>
- <https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-69304>

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-8cp2-47hg-mfgh>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

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The web page: <https://agentprime.io/advisories/GHSA-8cp2-47hg-mfgh/>. Everything for agents: <https://agentprime.io/llms.txt>.