Block the Serial API on specific sites
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
Specifies URL patterns for sites that aren't allowed to request access to a serial port. If not configured, Microsoft Edge uses the value from the DefaultSerialGuardSetting policy (if set), or the user's settings. For unmatched sites, the following order applies: 1. SerialAskForUrls (if matched). 2. DefaultSerialGuardSetting (if set). 3. User's settings. URL patterns in this policy must not conflict with those in SerialAskForUrls. This policy takes precedence. For detailed information about valid URL patterns, see https://go.microsoft.com/fwlink/?linkid=2095322. Example value: https://www.contoso.com [*.]contoso.edu
Registry
HKLM
Software\Policies\Microsoft\Edge HKCU
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: Block the Serial API on specific sites
; State: Enabled
; Scope: Computer (HKLM)
; Supported on: Microsoft Edge version 86, Windows 7 or later
[HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Edge\SerialBlockedForUrls]
; List values: enter one value per line in the builder UI.More formats (PowerShell, Intune, SCCM)
PowerShell
# Exported from gporais.com
# Policy: Block the Serial API on specific sites
# State: Enabled
# Scope: Computer (HKLM)
# Supported on: Microsoft Edge version 86, Windows 7 or later
$path = 'HKLM:\Software\Policies\Microsoft\Edge\SerialBlockedForUrls'
New-Item -Path $path -Force | Out-Null
# List values: enter one value per line in the builder UI.Intune 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: Block the Serial API on specific sites
# 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
}
# HKLM:\Software\Policies\Microsoft\Edge\SerialBlockedForUrls: List values: enter one value per line in the builder UI.
# No testable registry values are available for this state.
Write-Output 'Non-compliant'
exit 1
# === Remediation script ===
# Exported from gporais.com
# Policy: Block the Serial API on specific sites
# State: Enabled
# Scope: Computer (HKLM)
# Supported on: Microsoft Edge version 86, Windows 7 or later
$path = 'HKLM:\Software\Policies\Microsoft\Edge\SerialBlockedForUrls'
New-Item -Path $path -Force | Out-Null
# List values: enter one value per line in the builder UI.SCCM scripts
# Exported from gporais.com
# Policy: Block the Serial API on specific sites
# 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: Block the Serial API on specific sites
# 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
}
# HKLM:\Software\Policies\Microsoft\Edge\SerialBlockedForUrls: List values: enter one value per line in the builder UI.
# No testable registry values are available for this state.
Write-Output 'Non-compliant'
exit 1
# === Remediation script ===
# Exported from gporais.com
# Policy: Block the Serial API on specific sites
# State: Enabled
# Scope: Computer (HKLM)
# Supported on: Microsoft Edge version 86, Windows 7 or later
$path = 'HKLM:\Software\Policies\Microsoft\Edge\SerialBlockedForUrls'
New-Item -Path $path -Force | Out-Null
# List values: enter one value per line in the builder UI.Building a multi-setting collection? Add this setting and generate combined .reg / PowerShell / GPO scripts.