CVE-2026-85943: Reliable Multicast Transport Driver (RMCAST) Elevation of Privilege Vulnerability
Reliable Multicast Transport Driver (RMCAST) Elevation of Privilege Vulnerability
Other sources
Time-of-check time-of-use (toctou) race condition in Reliable Multicast Transport Driver (RMCAST) allows an authorized attacker to elevate privileges locally.
— 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 10.0.28000.3231Patch KB5127646 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.26200.9711Patch KB5127648 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.26300.9711Patch KB5127648 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.26100.9711Patch KB5127648 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 6.2.9200.26434Patch KB5126835 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.26100.33650Patch KB5126646 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 6.3.9600.23470Patch KB5126836 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.14393.9612Patch KB5126868 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.22631.7652Patch KB5126653 - Upgrade
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Fixed in 10.0.19044.7807Patch KB5126657 - Upgrade
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Fixed in 10.0.20348.5761Patch KB5126655 - Upgrade
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Fixed in 10.0.17763.9376Patch KB5126651
Event History
Frequently Asked Questions
Who can exploit this vulnerability?
An attacker must already be authorized on the affected system and able to execute an attack locally. The provided data does not indicate that remote or unauthenticated exploitation is possible.
Which systems should be assessed for exposure?
Assess Microsoft Windows 10 and Windows 11 endpoints, along with Windows Server 2012, 2012 R2, 2016, 2019, 2022, and 2025 systems. The available information does not distinguish particular editions, configurations, or patch levels within those products.
What impact could successful exploitation have?
Successful exploitation allows local privilege elevation. The supplied severity vector indicates high potential impact to confidentiality, integrity, and availability.