Control use of the Serial API
Verified with Microsoft Edge 152.0.4191.53 — updated on July 10, 2026
Supported on: Microsoft Edge version 86, Windows 7 or later
Path in the GPO console
Computer Configuration\Administrative Templates\Microsoft Edge User Configuration\Administrative Templates\Microsoft Edge Description
Set whether websites can access serial ports. You can completely block access or ask the user each time a website wants to get access to a serial port. Setting the policy to 3 lets websites ask for access to serial ports. Setting the policy to 2 denies access to serial ports. You can override this policy for specific URL patterns by using the 'SerialAskForUrls' (Allow the Serial API on specific sites) and 'SerialBlockedForUrls' (Block the Serial API on specific sites) policies. If you don't configure this policy, by default, websites can ask users whether they can access a serial port, and users can change this setting. Policy options mapping: * BlockSerial (2) = Do not allow any site to request access to serial ports via the Serial API * AskSerial (3) = Allow sites to ask for user permission to access a serial port Use the preceding information when configuring this policy.
Registry
Software\Policies\Microsoft\Edge Software\Policies\Microsoft\Edge Export Builder
BETAConfigure the state, scope and options, then generate .reg, PowerShell, Intune and SCCM outputs — or add the setting to a multi-setting collection.
These exports write the registry — this is not a managed GPO. ⓘ
Applying both scopes creates an ambiguous configuration (computer takes precedence over user). Only do this intentionally.
.reg file
Windows Registry Editor Version 5.00
; Exported from gporais.com
; Policy: Control use of the Serial API
; State: Enabled
; Scope: Computer (HKLM)
; Supported on: Microsoft Edge version 86, Windows 7 or later
[HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Edge]
"DefaultSerialGuardSetting"=dword:00000002More formats (PowerShell, Intune, SCCM)
PowerShell
# Exported from gporais.com
# Policy: Control use of the Serial API
# State: Enabled
# Scope: Computer (HKLM)
# Supported on: Microsoft Edge version 86, Windows 7 or later
$path = 'HKLM:\Software\Policies\Microsoft\Edge'
New-Item -Path $path -Force | Out-Null
Set-ItemProperty -Path $path -Name 'DefaultSerialGuardSetting' -Value 2 -Type DWordIntune XML
No direct Policy CSP / OMA-URI mapping for this policy. Use the Intune Remediation tab, or ingest the ADMX in Intune.Intune Remediation
# === Detection script ===
# Exported from gporais.com
# Policy: Control use of the Serial API
# State: Enabled
# Scope: Computer (HKLM)
# Supported on: Microsoft Edge version 86, Windows 7 or later
function Test-RegistryValue {
param(
[Parameter(Mandatory = $true)][string]$Path,
[Parameter(Mandatory = $true)][string]$Name,
[object]$Expected,
[ValidateSet('String', 'DWord', 'MultiString')][string]$Kind = 'String',
[switch]$Absent
)
try {
$item = Get-ItemProperty -LiteralPath $Path -Name $Name -ErrorAction Stop
} catch {
return $Absent.IsPresent
}
if ($Absent.IsPresent) { return $false }
$actual = $item.$Name
if ($Kind -eq 'DWord') { return ([int64]$actual) -eq ([int64]$Expected) }
if ($Kind -eq 'MultiString') {
$actualValues = @($actual)
$expectedValues = @($Expected)
if ($actualValues.Count -ne $expectedValues.Count) { return $false }
for ($i = 0; $i -lt $expectedValues.Count; $i++) {
if ([string]$actualValues[$i] -ne [string]$expectedValues[$i]) { return $false }
}
return $true
}
return [string]$actual -eq [string]$Expected
}
$checks = @(
(Test-RegistryValue -Path 'HKLM:\Software\Policies\Microsoft\Edge' -Name 'DefaultSerialGuardSetting' -Expected 2 -Kind DWord)
)
if ($checks -notcontains $false) {
Write-Output 'Compliant'
exit 0
}
Write-Output 'Non-compliant'
exit 1
# === Remediation script ===
# Exported from gporais.com
# Policy: Control use of the Serial API
# State: Enabled
# Scope: Computer (HKLM)
# Supported on: Microsoft Edge version 86, Windows 7 or later
$path = 'HKLM:\Software\Policies\Microsoft\Edge'
New-Item -Path $path -Force | Out-Null
Set-ItemProperty -Path $path -Name 'DefaultSerialGuardSetting' -Value 2 -Type DWordSCCM scripts
# Exported from gporais.com
# Policy: Control use of the Serial API
# State: Enabled
# Scope: Computer (HKLM)
# Supported on: Microsoft Edge version 86, Windows 7 or later
# SCCM Configuration Item guidance:
# Create a Configuration Item of type "Setting: Script".
# Discovery script: use the Detection script below.
# Remediation script: use the Remediation script below.
# Compliance rule: the Discovery script output equals 'Compliant'.
# === Detection script ===
# Exported from gporais.com
# Policy: Control use of the Serial API
# State: Enabled
# Scope: Computer (HKLM)
# Supported on: Microsoft Edge version 86, Windows 7 or later
function Test-RegistryValue {
param(
[Parameter(Mandatory = $true)][string]$Path,
[Parameter(Mandatory = $true)][string]$Name,
[object]$Expected,
[ValidateSet('String', 'DWord', 'MultiString')][string]$Kind = 'String',
[switch]$Absent
)
try {
$item = Get-ItemProperty -LiteralPath $Path -Name $Name -ErrorAction Stop
} catch {
return $Absent.IsPresent
}
if ($Absent.IsPresent) { return $false }
$actual = $item.$Name
if ($Kind -eq 'DWord') { return ([int64]$actual) -eq ([int64]$Expected) }
if ($Kind -eq 'MultiString') {
$actualValues = @($actual)
$expectedValues = @($Expected)
if ($actualValues.Count -ne $expectedValues.Count) { return $false }
for ($i = 0; $i -lt $expectedValues.Count; $i++) {
if ([string]$actualValues[$i] -ne [string]$expectedValues[$i]) { return $false }
}
return $true
}
return [string]$actual -eq [string]$Expected
}
$checks = @(
(Test-RegistryValue -Path 'HKLM:\Software\Policies\Microsoft\Edge' -Name 'DefaultSerialGuardSetting' -Expected 2 -Kind DWord)
)
if ($checks -notcontains $false) {
Write-Output 'Compliant'
exit 0
}
Write-Output 'Non-compliant'
exit 1
# === Remediation script ===
# Exported from gporais.com
# Policy: Control use of the Serial API
# State: Enabled
# Scope: Computer (HKLM)
# Supported on: Microsoft Edge version 86, Windows 7 or later
$path = 'HKLM:\Software\Policies\Microsoft\Edge'
New-Item -Path $path -Force | Out-Null
Set-ItemProperty -Path $path -Name 'DefaultSerialGuardSetting' -Value 2 -Type DWordBuilding a multi-setting collection? Add this setting and generate combined .reg / PowerShell / GPO scripts.