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Protect ForEach() property assignment on non-core types in Constrained Language Mode #28207

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Merged
Justin Chung (jshigetomi) merged 2 commits into from
Oct 19, 2026
Merged

Protect ForEach() property assignment on non-core types in Constrained Language Mode #28207

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97a6037
Throw in ForEach method if setting property in CLM (#170)
Oct 7, 2026
bb286ed
Merge branch 'master' into 170
jshigetomi Oct 14, 2026
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24 changes: 24 additions & 0 deletions src/System.Management.Automation/engine/runtime/Operations/MiscOps.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -3102,6 +3102,30 @@ internal static object ForEach(IEnumerator enumerator, object expression, object
else
{
var property = member as PSPropertyInfo;
if (languageMode == PSLanguageMode.ConstrainedLanguage
&& numArgs != 0
&& !CoreTypes.Contains(basedCurrent.GetType()))
{
if (SystemPolicy.GetSystemLockdownPolicy() != SystemEnforcementMode.Audit)
{
throw InterpreterError.NewInterpreterException(
current,
typeof(PSInvalidOperationException),
null,
"PropertySetterNotSupportedInConstrainedLanguage",
ParserStrings.PropertySetConstrainedLanguage);
}

SystemPolicy.LogWDACAuditMessage(
context: context,
title: ParameterBinderStrings.WDACBinderInvocationLogTitle,
message: StringUtil.Format(
ParameterBinderStrings.WDACBinderInvocationLogMessage,
name,
basedCurrent.GetType().FullName ?? string.Empty),
fqid: "MethodOrPropertyInvocationNotAllowed",
dropIntoDebugger: true);
}

switch (numArgs)
{
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41 changes: 41 additions & 0 deletions ...powershell/Modules/Microsoft.PowerShell.Security/ConstrainedLanguageRestriction.Tests.ps1
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Original file line number Diff line number Diff line change
Expand Up @@ -838,6 +838,47 @@ try

$expectedError.FullyQualifiedErrorId | Should -BeExactly "MethodInvocationNotSupportedInConstrainedLanguage"
}

It "Verify ForEach engine intrinsic method cannot set property values for non-core types when in constrained language mode" {

try
{
$ExecutionContext.SessionState.LanguageMode = 'ConstrainedLanguage'
& {
@($ExecutionContext.SessionState).ForEach('LanguageMode', 'FullLanguage')
}

throw "No Exception!"
}
catch
{
$expectedError = $_
}
finally
{
Invoke-LanguageModeTestingSupportCmdlet -EnableFullLanguageMode
}

$expectedError.FullyQualifiedErrorId | Should -BeExactly "PropertySetterNotSupportedInConstrainedLanguage"
}

It "Verify ForEach engine intrinsic method correctly allows setting property values for core types in constrained language mode" {

$validateSet = [ValidateSet]::new('test')
try
{
$ExecutionContext.SessionState.LanguageMode = 'ConstrainedLanguage'
& {
@($validateSet).ForEach('ErrorMessage', 'NewMessage')
}
}
finally
{
Invoke-LanguageModeTestingSupportCmdlet -EnableFullLanguageMode
}

$validateSet.ErrorMessage | Should -BeExactly 'NewMessage'
}
}

Describe "ThreadJob Constrained Language Tests" -Tags 'Feature','RequireAdminOnWindows' {
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