What is CVE-2026-78450?

CVE-2026-78450 is a security advisory published by Microsoft Security Response Center (MSRC) with Critical severity. Windows Reliable Multicast Transport Driver (RMCAST) Remote Code Execution Vulnerability

Which CVE IDs does CVE-2026-78450 cover?

CVE-2026-78450 covers the following CVE IDs: CVE-2026-78450. Each CVE has its own detail page on EchelonGraph Pulse with the synthesized EG score.

What is the CVSS v3 score of CVE-2026-78450?

CVE-2026-78450 has a CVSS v3 base score of 8.1, published by Microsoft Security Response Center (MSRC).

Which products are affected by CVE-2026-78450?

CVE-2026-78450 affects 8 products, including: 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; and others — see the full list on the advisory page.

CVE-2026-78450CriticalCVSS 8.1

Windows Reliable Multicast Transport Driver (RMCAST) Remote Code Execution Vulnerability

Vendor

Microsoft Security Response Center (MSRC)

Published

September 11, 2026

Last Modified

—

🔗 CVE IDs covered (1)

CVE-2026-78450 →

📋 Description

Use after free in Reliable Multicast Transport Driver (RMCAST) allows an unauthorized attacker to execute code over a network.

🎯 Affected products8

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)

✅ Remediation

KB5122876 (Security Update) — fixed build 10.0.17763.9245 KB5122882 (Security Update) — fixed build 10.0.20348.5622 KB5122871 (Security Update) — fixed build 10.0.26100.33438

🔗 References (7)

advisoryhttps://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-78450
patchhttps://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB5122876
referencehttps://support.microsoft.com/help/5122876
patchhttps://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB5122882
referencehttps://support.microsoft.com/help/5122882
patchhttps://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB5122871
referencehttps://support.microsoft.com/help/5122871