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Block-SmbShareAccess

Adds a deny ACE for a trustee to the security descriptor of the SMB share.

Networking / Security · Risk: High · Documentation Verified

Last verified: 2026-10-26

Microsoft SmbShare reference: Adds a deny ACE for a trustee to the security descriptor of the SMB share. The syntax and selected example below are adapted from the pinned Windows Server 2025 reference. Module availability, target configuration and delegated permissions determine whether it can run in your environment. Documentation and parameter text: Microsoft, CC BY 4.0; formatting adapted by Cmdlet World. No execution testing is claimed.

Block-SmbShareAccess [-Name] <String[]> [[-ScopeName] <String[]>] [-SmbInstance <SmbInstance>]
 [-AccountName <String[]>] [-Force] [-CimSession <CimSession[]>] [-ThrottleLimit <Int32>] [-AsJob] [-WhatIf]
 [-Confirm] [<CommonParameters>]

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Required permissions

Use an account with the target resource permissions documented for Block-SmbShareAccess. Modifying administrative cmdlets may require elevation or delegated administration. This catalog does not assert that ordinary users can execute the command.

Supported environments

Windows / SmbShare · Windows Server 2025 documentation; feature/module prerequisites apply

Parameters

-AccountName: Specifies the name of the account for the user who is being denied access to the share. Use a comma-separated list to deny share access to multiple accounts.
-AsJob: Runs the cmdlet as a background job. Use this parameter to run commands that take a long time to complete.
-CimSession: Runs the cmdlet in a remote session or on a remote computer. Enter a computer name or a session object, such as the output of a New-CimSession or Get-CimSession cmdlet. The default is the current session on the local computer.
-Confirm: Prompts you for confirmation before running the cmdlet.
-Force: Forces the command to run without asking for user confirmation.
-InputObject (required): Specifies the input object that is used in a pipeline command.
-Name (required): Specifies the name of the SMB share.
-ScopeName: Specifies the scope of the share specified by name.
-SmbInstance: Specifies the input to this cmdlet. You can use this parameter, or you can pipe the input to this cmdlet.
-ThrottleLimit: Specifies the maximum number of concurrent operations that can be established to run the cmdlet. If this parameter is omitted or a value of 0 is entered, then Windows PowerShell® calculates an optimum throttle limit for the cmdlet based on the number of CIM cmdlets that are running on the computer. The throttle limit applies only to the current cmdlet, not to the session or to the computer.
-WhatIf: Shows what would happen if the cmdlet runs. The cmdlet is not run.

Prerequisites

Windows with the SmbShare module and the Windows feature or management tools that provide it. Confirm target connectivity and version compatibility using the linked Microsoft reference.

Security considerations

This cmdlet changes system state. Review every target and parameter in the official reference, test outside production, and prepare an appropriate backup or rollback. Do not execute the example automatically.

Examples

Example 1: Add a deny ACS

Block-SmbShareAccess -Name VMFiles -AccountName Contoso\Guest

This command adds a deny ACE for a trustee to the security descriptor of an SMB share named VMFiles. Source: Microsoft, CC BY 4.0; transcript prompt/output removed. This example was not executed.

Sources

https://github.com/MicrosoftDocs/windows-powershell-docs/blob/b7645dd8c687139b28e845119da30ec670526507/docset/winserver2025-ps/SmbShare/Block-SmbShareAccess.md

https://learn.microsoft.com/powershell/module/smbshare/block-smbshareaccess?view=windowsserver2025-ps

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