CVE-2026-49172 is a Windows FTP Service remote code execution vulnerability caused by a heap-based buffer overflow. Microsoft rates it Critical with a CVSS v3.1 base score of 9.8 and a temporal score of 8.5. The vector is network-based, requires no privileges and no user interaction, and has high confidentiality, integrity, and availability impact. Microsoft states there is no public disclosure and no known exploitation, with exploit code maturity unproven. Because it affects a network service and can be triggered remotely without authentication or user interaction, it is relevant for enterprise systems where the FTP service is exposed.

Highlights:
- CVSS scores: Base 9.8 - Temporal 8.5
- 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 Less Likely; however, the vector is NETWORK with LOW attack complexity, NO privileges required, and NO user interaction.
- Severity for enterprise: High risk, especially for internet- or network-exposed FTP services, because remote exploitation does not require authentication or user interaction.
- Patch status: available; customer action required.

Affected systems:
- Windows 10 1607
- Windows 10 1809
- Windows 10 21H2
- Windows 10 22H2
- Windows 11 23H2
- Windows 11 24H2
- Windows 11 25H2
- Windows 11 26H1
- Windows 11 unspecified
- Windows Server 2019
- Windows Server 2022
- Windows Server 2025