Integer underflow in Windows and Windows Server - CVE-2026-54982
Published: July 17, 2026
Vulnerability identifier: #VU137940
CSH Severity: High
CVSS v4.0: 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/E:U/U:Amber
CVE-ID: CVE-2026-54982
CWE-ID: CWE-191
Exploitation vector: Adjecent network
Exploit availability:
No public exploit available
Vendor: Microsoft
Affected software:
Windows
Windows Server
Windows
Windows Server
Detailed vulnerability description
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.
How to mitigate CVE-2026-54982
Install security update from vendor's website.