CVE-2026-78444Critical
Microsoft Failover Cluster Remote Code Execution Vulnerability
Assessment
Untrusted pointer dereference in Windows Failover Cluster allows an unauthorized attacker to execute code over a network.
- Severity
- Critical
- CVSS base score
- 8.1CVSS:3.1/
AV:N/ AC:H/ PR:N/ UI:N/ S:U/ C:H/ I:H/ A:H/ E:U/ RL:O/ RC:C - Impact
- Remote Code Execution
- EPSS, next 30 days
- 0.7%Higher than 51.5% of scored CVEs · FIRST model run 26 Sep 2026 · about EPSS
- Exploitability
- Exploitation Less Likely
- Publicly disclosed
- No
- Customer action
- Required: apply the update
- Component
- Windows Failover Cluster
- Weakness
- CWE-822: Untrusted Pointer Dereference
- Issued by
- Microsoft
- Published
- 8 Sep 2026 · September 2026
- Last revised
- 8 Sep 2026
Updates that fix it
3 KBs| KB | Type | Restart | Applies to | Other CVEs |
|---|---|---|---|---|
| KB5122871 | Security Update | Required | Windows Server 2025, Windows Server 2025 (Server Core installation) | All CVEs in KB5122871 |
| KB5122876 | Security Update | Required | Windows 10 Version 1809 for 32-bit Systems, Windows 10 Version 1809 for x64-based Systems, Windows Server 2019 and 1 more | All CVEs in KB5122876 |
| KB5122882 | Security Update | Required | Windows Server 2022, Windows Server 2022 (Server Core installation) | All CVEs in KB5122882 |
Affected products
Windows8 affected products
- Windows 10 Version 1809 for 32-bit Systems
- Windows 10 Version 1809 for x64-based Systems
- Windows Server 2019
- Windows Server 2019 (Server Core installation)
- Windows Server 2022
- Windows Server 2022 (Server Core installation)
- Windows Server 2025
- Windows Server 2025 (Server Core installation)