Control use of the Web Serial API: registry value DefaultSerialGuardSettingComputerHKLM\Software\Policies\Mozilla\Firefox

Policy ID
DefaultSerialGuardSetting
Scope
Computer Configuration, User Configuration
Supported on
Firefox 151 or later
Source
Mozilla Firefox Policy Templates (version 8.3)
Category
Mozilla › Firefox

Registry

DefaultSerialGuardSetting

REG_DWORDComputerUser
Enabled value
Depends on the option value
Element
-
Options
ItemStored value
Do not allow any site to request access to serial ports via the Web Serial API2
Allow sites to ask the user to grant access to a serial port3
Apply with .reg · CMD · PowerShell
ComputerMachine-wide setting
.reg
Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\Software\Policies\Mozilla\Firefox]

; Options (use only one)
; Do not allow any site to request access to serial ports via the Web Serial API
"DefaultSerialGuardSetting"=dword:00000002
; Allow sites to ask the user to grant access to a serial port
"DefaultSerialGuardSetting"=dword:00000003
CMD
:: Options (use only one)

:: Do not allow any site to request access to serial ports via the Web Serial API
reg add "HKLM\Software\Policies\Mozilla\Firefox" /v "DefaultSerialGuardSetting" /t REG_DWORD /d 2 /f
:: Allow sites to ask the user to grant access to a serial port
reg add "HKLM\Software\Policies\Mozilla\Firefox" /v "DefaultSerialGuardSetting" /t REG_DWORD /d 3 /f
PowerShell
# Common: create the key
New-Item -Path 'HKLM:\Software\Policies\Mozilla\Firefox' -Force | Out-Null

# Options (use only one)
# Do not allow any site to request access to serial ports via the Web Serial API
New-ItemProperty -Path 'HKLM:\Software\Policies\Mozilla\Firefox' -Name 'DefaultSerialGuardSetting' -PropertyType DWord -Value 2 -Force | Out-Null
# Allow sites to ask the user to grant access to a serial port
New-ItemProperty -Path 'HKLM:\Software\Policies\Mozilla\Firefox' -Name 'DefaultSerialGuardSetting' -PropertyType DWord -Value 3 -Force | Out-Null
UserPer-account setting
.reg
Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Policies\Mozilla\Firefox]

; Options (use only one)
; Do not allow any site to request access to serial ports via the Web Serial API
"DefaultSerialGuardSetting"=dword:00000002
; Allow sites to ask the user to grant access to a serial port
"DefaultSerialGuardSetting"=dword:00000003
CMD
:: Options (use only one)

:: Do not allow any site to request access to serial ports via the Web Serial API
reg add "HKCU\Software\Policies\Mozilla\Firefox" /v "DefaultSerialGuardSetting" /t REG_DWORD /d 2 /f
:: Allow sites to ask the user to grant access to a serial port
reg add "HKCU\Software\Policies\Mozilla\Firefox" /v "DefaultSerialGuardSetting" /t REG_DWORD /d 3 /f
PowerShell
# Common: create the key
New-Item -Path 'HKCU:\Software\Policies\Mozilla\Firefox' -Force | Out-Null

# Options (use only one)
# Do not allow any site to request access to serial ports via the Web Serial API
New-ItemProperty -Path 'HKCU:\Software\Policies\Mozilla\Firefox' -Name 'DefaultSerialGuardSetting' -PropertyType DWord -Value 2 -Force | Out-Null
# Allow sites to ask the user to grant access to a serial port
New-ItemProperty -Path 'HKCU:\Software\Policies\Mozilla\Firefox' -Name 'DefaultSerialGuardSetting' -PropertyType DWord -Value 3 -Force | Out-Null