CVE-2025-49751

Host denial of service via missing synchronization

Published Aug 12, 2025 · Updated Feb 13, 2026

Missing synchronization in Windows Hyper-V allows remote authenticated users on an adjacent network to crash the host. Microsoft has not disclosed which Hyper-V operation lacks synchronization or the request sequence that triggers the failure. Exploitation requires low privileges and adjacent-network reachability; the documented consequence is availability loss without data disclosure or modification.

CVSS severity6.8
Medium
EPSS probability0.47%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Missing synchronization in Windows Hyper-V allows remote authenticated users on an adjacent network to crash the host. Microsoft has not disclosed which Hyper-V operation lacks synchronization or the request sequence that triggers the failure. Exploitation requires low privileges and adjacent-network reachability; the documented consequence is availability loss without data disclosure or modification.

The record

CVE
CVE-2025-49751
Published
Aug 12, 2025
Updated
Feb 13, 2026
Vendor
Microsoft
Product
Windows Server 2019
Classifications
CWE-820, T1499
Attack vector
adjacent
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 12, 2025CVE publishedPublication date reported by the CVE source.
  2. Feb 13, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=10.0.17763.0 <10.0.17763.7678

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesauthenticated

What is affected?

Microsoft · Windows Server 2019version=10.0.17763.0 <10.0.17763.7678
Microsoft · Windows Server 2025 (Server Core installation)version=10.0.26100.0 <10.0.26100.4946
Microsoft · Windows Server 2016 (Server Core installation)version=10.0.14393.0 <10.0.14393.8330
Microsoft · Windows 11, version 24H2version=10.0.26100.0 <10.0.26100.4946
Microsoft · Windows 10 Version 21H2version=10.0.19044.0 <10.0.19044.6216
Microsoft · Windows Server 2022, 23H2 Edition (Server Core installation)version=10.0.25398.0 <10.0.25398.1791
Microsoft · Windows Server 2016version=10.0.14393.0 <10.0.14393.8330
Microsoft · Windows 11 Version 22H3version=10.0.22631.0 <10.0.22631.5768
Microsoft · Windows 10 Version 22H2version=10.0.19045.0 <10.0.19045.6216
Microsoft · Windows Server 2019 (Server Core installation)version=10.0.17763.0 <10.0.17763.7678
Microsoft · Windows 11 Version 23H2version=10.0.22631.0 <10.0.22631.5768
Microsoft · Windows 11, version 22H2version=10.0.22621.0 <10.0.22621.5768
Microsoft · Windows 10 Version 1607version=10.0.14393.0 <10.0.14393.8330
Microsoft · Windows Server 2022version=10.0.20348.0 <10.0.20348.4052
Microsoft · Windows Server 2025version=10.0.26100.0 <10.0.26100.4946
Microsoft · Windows 10 Version 1809version=10.0.17763.0 <10.0.17763.7678

Published CVSS scores

6.8Microsoft CorporationCVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-820Missing Synchronization
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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