---
id: CVE-2026-54982
title: >-
  Windows Reliable Multicast Transport Driver (RMCAST) Remote Code Execution
  Vulnerability
summary: >-
  Integer underflow (wrap or wraparound) in Reliable Multicast Transport Driver
  (RMCAST) allows an unauthorized attacker to execute code over an adjacent
  network.
severity: high
cvss: 8.8
cvssVector: 'CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C'
cvssSource: cna
cwe:
  - CWE-191
vendor: Microsoft
product: Windows 10 Version 1607
affected:
  - windows_10_version_1607 >= 10.0.14393.0 < 10.0.14393.9339
  - windows_10_version_1809 >= 10.0.17763.0 < 10.0.17763.9020
  - windows_10_version_21h2 >= 10.0.19044.0 < 10.0.19044.7548
  - windows_10_version_22h2 >= 10.0.19045.0 < 10.0.19045.7548
  - windows_11_version_24h2 >= 10.0.26100.0 < 10.0.26100.8875
  - windows_11_version_25h2 >= 10.0.26200.0 < 10.0.26200.8875
  - windows_11_version_26h1 >= 10.0.28000.0 < 10.0.28000.2525
  - windows_server_2012 >= 6.2.9200.0 < 6.2.9200.26226
  - windows_server_2012_server_core_installation >= 6.2.9200.0 < 6.2.9200.26226
  - windows_server_2012_r2 >= 6.3.9600.0 < 6.3.9600.23291
  - >-
    windows_server_2012_r2_server_core_installation >= 6.3.9600.0 <
    6.3.9600.23291
  - windows_server_2016 >= 10.0.14393.0 < 10.0.14393.9339
  - >-
    windows_server_2016_server_core_installation >= 10.0.14393.0 <
    10.0.14393.9339
  - windows_server_2019 >= 10.0.17763.0 < 10.0.17763.9020
  - >-
    windows_server_2019_server_core_installation >= 10.0.17763.0 <
    10.0.17763.9020
  - windows_server_2022 >= 10.0.20348.0 < 10.0.20348.5386
  - windows_server_2025 >= 10.0.26100.0 < 10.0.26100.33158
  - >-
    windows_server_2025_server_core_installation >= 10.0.26100.0 <
    10.0.26100.33158
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-07-15T03:59:07.223027Z'
published: '2026-07-14'
updated: '2026-09-17'
sourceUpdated: '2026-09-17T22:28:55.868Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-54982'
references:
  - url: 'https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-54982'
    label: >-
      Windows Reliable Multicast Transport Driver (RMCAST) Remote Code Execution
      Vulnerability
tags:
  - cve.org
epss: 0.00535
epssPercentile: 0.44105
ingestedAt: '2026-09-08T17:06:31.930Z'
---

## Overview

Integer underflow (wrap or wraparound) in Reliable Multicast Transport Driver (RMCAST) allows an unauthorized attacker to execute code over an adjacent network.

## Affected

- `windows_10_version_1607 >= 10.0.14393.0 < 10.0.14393.9339`
- `windows_10_version_1809 >= 10.0.17763.0 < 10.0.17763.9020`
- `windows_10_version_21h2 >= 10.0.19044.0 < 10.0.19044.7548`
- `windows_10_version_22h2 >= 10.0.19045.0 < 10.0.19045.7548`
- `windows_11_version_24h2 >= 10.0.26100.0 < 10.0.26100.8875`
- `windows_11_version_25h2 >= 10.0.26200.0 < 10.0.26200.8875`
- `windows_11_version_26h1 >= 10.0.28000.0 < 10.0.28000.2525`
- `windows_server_2012 >= 6.2.9200.0 < 6.2.9200.26226`
- `windows_server_2012_server_core_installation >= 6.2.9200.0 < 6.2.9200.26226`
- `windows_server_2012_r2 >= 6.3.9600.0 < 6.3.9600.23291`
- `windows_server_2012_r2_server_core_installation >= 6.3.9600.0 < 6.3.9600.23291`
- `windows_server_2016 >= 10.0.14393.0 < 10.0.14393.9339`
- `windows_server_2016_server_core_installation >= 10.0.14393.0 < 10.0.14393.9339`
- `windows_server_2019 >= 10.0.17763.0 < 10.0.17763.9020`
- `windows_server_2019_server_core_installation >= 10.0.17763.0 < 10.0.17763.9020`
- `windows_server_2022 >= 10.0.20348.0 < 10.0.20348.5386`
- `windows_server_2025 >= 10.0.26100.0 < 10.0.26100.33158`
- `windows_server_2025_server_core_installation >= 10.0.26100.0 < 10.0.26100.33158`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.