# Windows MIDI Service Module Elevation of Privileges Vulnerability

CVE record · `CVE-2026-78464`

- **Identifiers:** `CVE-2026-78464`
- **State:** Confirmed
- **Severity:** CVSS 7.0 High
- **Critical:** No
- **CNA:** microsoft
- **Weakness (CWE):** [CWE-367](https://cwe.mitre.org/data/definitions/367.html)
- **Tags:** [Race condition](https://agentprime.io/advisories/tag/race-condition.md)
- **Technologies:** [Microsoft Windows 11 Version 24H2](https://agentprime.io/advisories/technology/microsoft-windows-11-version-24h2.md) · [Microsoft Windows 11 Version 25H2](https://agentprime.io/advisories/technology/microsoft-windows-11-version-25h2.md) · [Microsoft Windows 11 version 26H1](https://agentprime.io/advisories/technology/microsoft-windows-11-version-26h1.md)
- **Published:** 8 Sept 2026
- **Updated:** 10 Nov 2026
- **Reviewed by a person:** No

Published by the CVE Program (CNA: microsoft) at 8 Sept 2026, 17:18 UTC. agentprime has not analysed this yet, so whether it affects any app is not known. This CVE names a vendor and product rather than a package, so the lockfile check doesn’t match it.

## Affected products, as the CNA wrote them

- Vendor: Microsoft. Product: Windows 11 Version 24H2.
  - affected: `10.0.26100.0 to before 10.0.26100.9445` (custom)
- Vendor: Microsoft. Product: Windows 11 Version 25H2.
  - affected: `10.0.26200.0 to before 10.0.26200.9445` (custom)
- Vendor: Microsoft. Product: Windows 11 version 26H1.
  - affected: `10.0.28000.0 to before 10.0.28000.2954` (custom)

## Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

> Windows MIDI Service Module is vulnerable in Windows 11 versions 24H2 (before 10.0.26100.9445), 25H2 (before 10.0.26200.9445) and 26H1 (before 10.0.28000.2954). A race condition between checking and using a resource lets an attacker who already has local, authorized access elevate their privileges. Users should upgrade to the fixed builds listed for their Windows version. The source gives few other details.

Written 11 Nov 2026.

## Not analysed yet

We haven’t published our own analysis of this CVE. If a person reviews it, this page will say what’s affected and what has to be true for it to matter.

## Severity and exploitation

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

- **CISA KEV:** Not listed.
- **EPSS:** 0.0020, the 10th percentile, on 11 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 8 Sept 2026, 17:18 UTC: [Confirmed by the CVE List](https://www.cve.org/CVERecord?id=CVE-2026-78464)
- 31 Oct 2026, 16:26 UTC: First seen by agentprime

## Sources

- [CVE List: CVE-2026-78464](https://www.cve.org/CVERecord?id=CVE-2026-78464)
- [NVD: CVE-2026-78464](https://nvd.nist.gov/vuln/detail/CVE-2026-78464)

### References from the CNA

- <https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-78464> (vendor-advisory, patch)

Facts on this page come from the CVE List as the CNA published them, with CVSS from the sources named above, CISA KEV and FIRST EPSS. Vendors, products and versions are shown as the CNA wrote them. We don’t reproduce the CVE’s description.

## Check whether this affects you

This CVE names a vendor and product rather than a package, so the lockfile check doesn’t match it. Compare the affected versions above with what you run.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), `get_advisory` returns this record and `search_advisories` finds related ones. Setup: <https://agentprime.io/mcp.md>
- As JSON: <https://api.agentprime.io/v1/advisories/CVE-2026-78464>
- Everything that needs attention now: <https://agentprime.io/advisories/critical.md>

---

The web page: <https://agentprime.io/advisories/CVE-2026-78464/>. Everything for agents: <https://agentprime.io/llms.txt>.