CVE-2026-78449: Windows Reliable Multicast Transport Driver (RMCAST) Remote Code Execution Vulnerability
Use after free in Reliable Multicast Transport Driver (RMCAST) allows an unauthorized attacker to execute code over a network.
Other sources
Windows Reliable Multicast Transport Driver (RMCAST) Remote Code Execution Vulnerability
— Microsoft
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.19045.7725Patch KB5122878 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.26200.9445Patch KB5124008 - Upgrade
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Fixed in 6.2.9200.26349Patch KB5123065 - Upgrade
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Fixed in 6.3.9600.23397Patch KB5123066 - Upgrade
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Fixed in 10.0.28000.2954Patch KB5124012 - Upgrade
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Fixed in 10.0.14393.9512Patch KB5123099 - Upgrade
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Fixed in 10.0.26100.9445Patch KB5124008 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.26100.33438Patch KB5122871 - Upgrade
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Fixed in 10.0.22631.7582Patch KB5122880 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.19044.7725Patch KB5122878 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.20348.5622Patch KB5122882 - Upgrade
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Fixed in 10.0.17763.9245Patch KB5122876
Event History
Frequently Asked Questions
What access does an attacker need to exploit this issue?
The vulnerability is remotely exploitable over a network and does not require attacker privileges or user interaction. Exploitation has high attack complexity.
Which systems should be prioritized for review?
Review Microsoft Windows 10, Windows 11, and the listed Windows Server releases: 2012, 2012 R2, 2016, 2019, 2022, and 2025. The available data does not identify affected build numbers, configurations, or update levels.
What is the potential impact of successful exploitation?
Successful exploitation can allow unauthorized remote code execution. The supplied severity data indicates high potential impact to confidentiality, integrity, and availability.