# Windows System Secure Feature Bypass Vulnerability

CVE record · `CVE-2026-50418`

- **Identifiers:** `CVE-2026-50418`
- **State:** Confirmed
- **Severity:** CVSS 5.1 Medium
- **Critical:** No
- **CNA:** microsoft
- **Weakness (CWE):** [CWE-284](https://cwe.mitre.org/data/definitions/284.html)
- **Tags:** [Broken access control](https://agentprime.io/advisories/tag/access-control.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) · [Microsoft Windows Server 2022](https://agentprime.io/advisories/technology/microsoft-windows-server-2022.md) · [Microsoft Windows Server 2025](https://agentprime.io/advisories/technology/microsoft-windows-server-2025.md) · [Microsoft Windows Server 2025 (Server Core installation)](https://agentprime.io/advisories/technology/microsoft-windows-server-2025-server-core-installation.md)
- **Published:** 14 Jul 2026
- **Updated:** 10 Nov 2026
- **Reviewed by a person:** No

Published by the CVE Program (CNA: microsoft) at 14 Jul 2026, 17:07 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 10.0.26100.8875` (custom)
- Vendor: Microsoft. Product: Windows 11 Version 25H2.
  - affected: `10.0.26200.0 to before 10.0.26200.8875` (custom)
- Vendor: Microsoft. Product: Windows 11 version 26H1.
  - affected: `10.0.28000.0 to before 10.0.28000.2525` (custom)
- Vendor: Microsoft. Product: Windows Server 2022.
  - affected: `10.0.20348.0 to before 10.0.20348.5386` (custom)
- Vendor: Microsoft. Product: Windows Server 2025.
  - affected: `10.0.26100.0 to before 10.0.26100.33158` (custom)
- Vendor: Microsoft. Product: Windows Server 2025 (Server Core installation).
  - affected: `10.0.26100.0 to before 10.0.26100.33158` (custom)

## Machine-written summary

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

> Microsoft Windows 11 versions 24H2, 25H2 and 26H1, and Windows Server 2022 and 2025 (including Server Core installations), are affected by an improper access control flaw that allows a security feature to be bypassed. An attacker needs local access to the system, and the source gives few details on what else they can do. Upgrade to Windows 11 24H2 build 10.0.26100.8875 or later, 25H2 build 10.0.26200.8875 or later, 26H1 build 10.0.28000.2525 or later, Windows Server 2022 build 10.0.20348.5386 or later, or Windows Server 2025 build 10.0.26100.33158 or later.

Written 13 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

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

- **CISA KEV:** Not listed.
- **EPSS:** 0.0027, the 18th percentile, on 13 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 14 Jul 2026, 17:07 UTC: [Confirmed by the CVE List](https://www.cve.org/CVERecord?id=CVE-2026-50418)

## Sources

- [CVE List: CVE-2026-50418](https://www.cve.org/CVERecord?id=CVE-2026-50418)
- [NVD: CVE-2026-50418](https://nvd.nist.gov/vuln/detail/CVE-2026-50418)

### References from the CNA

- <https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-50418> (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-2026-50418>
- Everything that needs attention now: <https://agentprime.io/advisories/critical.md>

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The web page: <https://agentprime.io/advisories/CVE-2026-50418/>. Everything for agents: <https://agentprime.io/llms.txt>.