CVE-2026-54995 is a Windows Reliable Multicast Transport Driver (RMCAST) use-after-free vulnerability that can lead to remote code execution. Microsoft rates it CVSS v3.1 base 8.1 (High) with a temporal score of 7.1; the vector is NETWORK, attack complexity is HIGH, privileges required are NONE, user interaction is NONE, and scope is unchanged. The impact is HIGH for confidentiality, integrity, and availability. Microsoft says it is not publicly disclosed, not exploited, and exploit code maturity is UNPROVEN, with exploitation unlikely. Because it is network-reachable and requires no authentication or user interaction, it is relevant for enterprise environments where the affected service is exposed.

Highlights:
- CVSS scores: Base 8.1 - Temporal 7.1
- Exploit status & code maturity: Publicly Disclosed: No; Exploited: No; Exploit Code Maturity: UNPROVEN.
- Impact: Remote Code Execution with HIGH confidentiality, integrity, and availability impacts.
- Exploitation likelihood: Exploitation Unlikely; network vector, NO privileges required, and NO user interaction, but attack complexity is HIGH.
- Severity for enterprise: High severity due to remote code execution over the network, but the HIGH attack complexity and lack of known exploitation reduce immediate observed risk compared with easier-to-exploit network RCE issues.
- Patch status: available

Affected systems:
- Windows 10 1607
- Windows 10 1809
- Windows 10 21H2
- Windows 10 22H2
- Windows 11 24H2
- Windows 11 25H2
- Windows 11 26H1
- Windows 11 unspecified
- Windows Server 2012
- Windows Server 2012 R2
- Windows Server 2016
- Windows Server 2019
- Windows Server 2022
- Windows Server 2025