Microsoft Windows up to Server 2025 Hyper-V denial of service

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
6.5	$0-$5k	0.00

Summaryinfo

A vulnerability was found in Microsoft Windows. It has been classified as critical. This vulnerability affects unknown code of the component Hyper-V. This manipulation causes denial of service. This vulnerability is tracked as CVE-2025-49751. The attack is possible to be carried out remotely. No exploit exists. Applying a patch is the recommended action to fix this issue.

Detailsinfo

A vulnerability was found in Microsoft Windows. It has been declared as critical. Affected by this vulnerability is an unknown code block of the component Hyper-V. The manipulation with an unknown input leads to a denial of service vulnerability. The CWE definition for the vulnerability is CWE-404. The product does not release or incorrectly releases a resource before it is made available for re-use. As an impact it is known to affect availability. The summary by CVE is:

Missing synchronization in Windows Hyper-V allows an authorized attacker to deny service over an adjacent network.

The weakness was disclosed 08/12/2025 as confirmed security update guide (Website). The advisory is shared at msrc.microsoft.com. This vulnerability is known as CVE-2025-49751. The exploitation appears to be easy. The attack can be launched remotely. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 11/21/2025). MITRE ATT&CK project uses the attack technique T1499 for this issue.

The vulnerability scanner Nessus provides a plugin with the ID 249138 (KB5063875: Windows 11 version 22H2 / Windows 11 version 23H2 Security Update (August 2025)), which helps to determine the existence of the flaw in a target environment.

Applying a patch is able to eliminate this problem. A possible mitigation has been published immediately after the disclosure of the vulnerability.

The vulnerability is also documented in the databases at Tenable (249138) and CERT Bund (WID-SEC-2025-1790). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Affected

• Hitachi Virtual Storage Platform
• Microsoft Windows Server 2022
• Microsoft Windows Server
• Microsoft Windows 10
• Microsoft Windows Server 2016
• Microsoft Windows Server 2019
• Microsoft Windows 11
• Microsoft Windows Server 2012
• Microsoft Windows Server 2012 R2
• Microsoft Windows Server 2025
• Microsoft Windows

Productinfo

Type

• Operating System

Vendor

• Microsoft

Name

• Windows

Version

• 10 21H2
• 10 22H2
• 10 1607
• 10 1809
• 11 22H2
• 11 23H2
• 11 24H2
• Server 2016
• Server 2019
• Server 2022
• Server 2022 23H2
• Server 2025

License

• commercial

Website

• Vendor: https://www.microsoft.com/
• Product: https://www.microsoft.com/en-us/windows

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 7.1
VulDB Meta Temp Score: 6.5

VulDB Base Score: 7.7
VulDB Temp Score: 6.7
VulDB Vector: 🔒
VulDB Reliability: 🔍

Vendor Base Score (Microsoft): 6.8
Vendor Vector (Microsoft): 🔒

CNA Base Score: 6.8
CNA Vector (Microsoft): 🔒

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock

VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Denial of service
CWE: CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Unproven

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Nessus ID: 249138
Nessus Name: KB5063875: Windows 11 version 22H2 / Windows 11 version 23H2 Security Update (August 2025)

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Patch
Status: 🔍

Reaction Time: 🔒
0-Day Time: 🔒
Exposure Time: 🔒

Timelineinfo

08/12/2025 VulDB entry created
08/12/2025 +0 days Advisory disclosed
08/12/2025 +0 days Countermeasure disclosed
11/21/2025 +101 days VulDB entry last update

Sourcesinfo

Vendor: microsoft.com
Product: microsoft.com

Advisory: msrc.microsoft.com
Status: Confirmed

CVE: CVE-2025-49751 (🔒)
GCVE (CVE): GCVE-0-2025-49751
GCVE (VulDB): GCVE-100-319597
CERT Bund: WID-SEC-2025-1790 - Microsoft Windows und Windows Server: Mehrere Schwachstellen

scip Labs: https://www.scip.ch/en/?labs.20161215

Entryinfo

Created: 08/12/2025 19:19
Updated: 11/21/2025 11:41
Changes: 08/12/2025 19:19 (1), 08/12/2025 19:20 (34), 08/12/2025 19:23 (34), 08/13/2025 06:20 (2), 08/16/2025 02:50 (13), 11/21/2025 11:41 (7)
Complete: 🔍
Cache ID: 216::103

If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Discussion

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