Integer underflow in Microsoft Windows and Windows Server - CVE-2026-54982
Published: July 17, 2026
Vulnerability identifier: #VU137940
CSH Severity: High
CVSS v4: 8.7 [CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-54982
CWE-ID: CWE-191
Exploitation vector: Adjecent network
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to execute arbitrary code.
The vulnerability exists due to integer underflow in Reliable Multicast Transport Driver (RMCAST) when processing network traffic on the same network segment. A remote attacker can send specially crafted network traffic to execute arbitrary code.
The attack is limited to systems on the same network segment as the attacker.
Affected software
Microsoft Windows
Windows Server
Windows Server
How to mitigate CVE-2026-54982
Install security update from vendor's website.
Microsoft Windows - addressed in versions 10 21H2 10.0.19044.7548, 10 22H2 10.0.19045.7548, 10 1607 10.0.14393.9339, 10 1809 10.0.17763.9020, 11 24H2 10.0.26100.8875, 11 25H2 10.0.26200.8875, 11 26H1 10.0.28000.2525
Windows Server - addressed in versions 2012 R2 6.3.9600.23291, 2012 6.2.9200.26226, 2016 10.0.14393.9339, 2019 10.0.17763.9020, 2022 10.0.20348.5386, 2025 10.0.26100.33158
Windows Server - addressed in versions 2012 R2 6.3.9600.23291, 2012 6.2.9200.26226, 2016 10.0.14393.9339, 2019 10.0.17763.9020, 2022 10.0.20348.5386, 2025 10.0.26100.33158