Microsoft Windows up to Server 2025 Ancillary Function Driver for WinSock use after free

CVSS Meta Temp Score
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CTI Interest Score
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6.4$5k-$25k0.00

Summaryinfo

A vulnerability marked as critical has been reported in Microsoft Windows. Affected by this vulnerability is an unknown functionality of the component Ancillary Function Driver for WinSock. The manipulation leads to use after free. This vulnerability is documented as CVE-2026-42911. The attack needs to be performed locally. There is not any exploit available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in Microsoft Windows. It has been rated as critical. This issue affects an unknown code of the component Ancillary Function Driver for WinSock. The manipulation with an unknown input leads to a use after free vulnerability. Using CWE to declare the problem leads to CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

Use after free in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally.

The weakness was released 06/09/2026 as confirmed security update guide (Website). It is possible to read the advisory at msrc.microsoft.com. The identification of this vulnerability is CVE-2026-42911. The exploitation is known to be difficult. Attacking locally is a requirement. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 09/19/2026).

Upgrading to version 6.3.9600.23228 eliminates this vulnerability. A possible mitigation has been published immediately after the disclosure of the vulnerability.

The vulnerability is also documented in the vulnerability database at CERT Bund (WID-SEC-2026-1849). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Affected

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

Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 7.0
VulDB Meta Temp Score: 6.4

VulDB Base Score: 7.0
VulDB Temp Score: 6.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

Vendor Base Score (Microsoft): 7.0
Vendor Vector (Microsoft): 🔒

CNA Base Score: 7.0
CNA Vector (Microsoft): 🔒

CVSSv2info

AVACAuCIA
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💳💳💳💳💳💳
💳💳💳💳💳💳
VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Use after free
CWE: CWE-416 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: No

Availability: 🔒
Status: Unproven

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

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

Upgrade: Windows 6.3.9600.23228

Timelineinfo

06/09/2026 VulDB entry created
06/09/2026 +0 days Advisory disclosed
06/09/2026 +0 days Countermeasure disclosed
09/19/2026 +101 days VulDB entry last update

Sourcesinfo

Vendor: microsoft.com
Product: microsoft.com

Advisory: msrc.microsoft.com
Status: Confirmed

CVE: CVE-2026-42911 (🔒)
GCVE (CVE): GCVE-0-2026-42911
GCVE (VulDB): GCVE-100-369611
CERT Bund: WID-SEC-2026-1849 - Microsoft Windows: Mehrere Schwachstellen

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

Entryinfo

Created: 06/09/2026 19:22
Updated: 09/19/2026 00:45
Changes: 06/09/2026 19:22 (18), 06/09/2026 19:23 (20), 06/09/2026 19:26 (32), 06/14/2026 01:08 (11), 09/19/2026 00:45 (7)
Complete: 🔍
Cache ID: 216::103

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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