Enable strict MIME type checking for worker scripts
Verified with Google Chrome — updated on July 10, 2026
Supported on: Microsoft Windows 7 or later
Path in the GPO console
Computer Configuration\Administrative Templates\Google\Google Chrome User Configuration\Administrative Templates\Google\Google Chrome Description
This policy enables strict MIME type checking for worker scripts. When enabled or unset, then worker scripts will use strict MIME type checking for JavaScript, which is the new default behaviour. Worker scripts with legacy MIME types will be rejected. When disabled, then worker scripts will use lax MIME type checking, so that worker scripts with legacy MIME types, e.g. text/ascii, will continue to be loaded and executed. Browsers traditionally used lax MIME type checking, so that resources with a number of legacy MIME types were supported. E.g. for JavaScript resources, text/ascii is a legacy supported MIME type. This may cause security issues, by allowing to load resources as scripts that were never intended to be used as such. Chrome will transition to use strict MIME type checking in the near future. The enabled policy will track the default behaviour. Disabling this policy allows administrators to retain the legacy behaviour, if desired. See https://html.spec.whatwg.org/multipage/scripting.html#scriptingLanguage for details about JavaScript / ECMAScript media types.
Registry
Software\Policies\Google\Chrome Software\Policies\Google\Chrome Value name: StrictMimetypeCheckForWorkerScriptsEnabled
Enabled: StrictMimetypeCheckForWorkerScriptsEnabled = 1
Disabled: StrictMimetypeCheckForWorkerScriptsEnabled = 0
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: Enable strict MIME type checking for worker scripts
; State: Enabled
; Scope: Computer (HKLM)
; Supported on: Microsoft Windows 7 or later
[HKEY_LOCAL_MACHINE\Software\Policies\Google\Chrome]
"StrictMimetypeCheckForWorkerScriptsEnabled"=dword:00000001More formats (PowerShell, Intune, SCCM)
PowerShell
# Exported from gporais.com
# Policy: Enable strict MIME type checking for worker scripts
# State: Enabled
# Scope: Computer (HKLM)
# Supported on: Microsoft Windows 7 or later
$path = 'HKLM:\Software\Policies\Google\Chrome'
New-Item -Path $path -Force | Out-Null
Set-ItemProperty -Path $path -Name 'StrictMimetypeCheckForWorkerScriptsEnabled' -Value 1 -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: Enable strict MIME type checking for worker scripts
# State: Enabled
# Scope: Computer (HKLM)
# Supported on: Microsoft 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
}
$checks = @(
(Test-RegistryValue -Path 'HKLM:\Software\Policies\Google\Chrome' -Name 'StrictMimetypeCheckForWorkerScriptsEnabled' -Expected 1 -Kind DWord)
)
if ($checks -notcontains $false) {
Write-Output 'Compliant'
exit 0
}
Write-Output 'Non-compliant'
exit 1
# === Remediation script ===
# Exported from gporais.com
# Policy: Enable strict MIME type checking for worker scripts
# State: Enabled
# Scope: Computer (HKLM)
# Supported on: Microsoft Windows 7 or later
$path = 'HKLM:\Software\Policies\Google\Chrome'
New-Item -Path $path -Force | Out-Null
Set-ItemProperty -Path $path -Name 'StrictMimetypeCheckForWorkerScriptsEnabled' -Value 1 -Type DWordSCCM scripts
# Exported from gporais.com
# Policy: Enable strict MIME type checking for worker scripts
# State: Enabled
# Scope: Computer (HKLM)
# Supported on: Microsoft 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: Enable strict MIME type checking for worker scripts
# State: Enabled
# Scope: Computer (HKLM)
# Supported on: Microsoft 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
}
$checks = @(
(Test-RegistryValue -Path 'HKLM:\Software\Policies\Google\Chrome' -Name 'StrictMimetypeCheckForWorkerScriptsEnabled' -Expected 1 -Kind DWord)
)
if ($checks -notcontains $false) {
Write-Output 'Compliant'
exit 0
}
Write-Output 'Non-compliant'
exit 1
# === Remediation script ===
# Exported from gporais.com
# Policy: Enable strict MIME type checking for worker scripts
# State: Enabled
# Scope: Computer (HKLM)
# Supported on: Microsoft Windows 7 or later
$path = 'HKLM:\Software\Policies\Google\Chrome'
New-Item -Path $path -Force | Out-Null
Set-ItemProperty -Path $path -Name 'StrictMimetypeCheckForWorkerScriptsEnabled' -Value 1 -Type DWordBuilding a multi-setting collection? Add this setting and generate combined .reg / PowerShell / GPO scripts.