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Validate remote module names used by Save-Help #28400

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5512980
Sanitize remote module name used by Save-Help (#241)
Nov 5, 2026
72b4876
Merge branch 'master' into 241bp
jshigetomi Nov 12, 2026
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21 changes: 21 additions & 0 deletions src/System.Management.Automation/help/UpdatableHelpCommandBase.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -32,6 +32,12 @@ public class UpdatableHelpCommandBase : PSCmdlet

internal int activityId;
private readonly Dictionary<string, UpdatableHelpExceptionContext> _exceptions;
private static readonly char[] s_pathTraversalChars =
#if UNIX
['\\', '/'];
#else
['\\', '/', ':'];
#endif

#region Parameters

Expand Down Expand Up @@ -272,6 +278,21 @@ private void ProcessSingleModuleObject(PSModuleInfo module, ExecutionContext con
return;
}

if (string.IsNullOrEmpty(module.Name) || module.Name.IndexOfAny(s_pathTraversalChars) >= 0 || module.Name is "." or "..")
{
if (!noErrors)
{
ProcessException(module.Name, culture: null, new UpdatableHelpSystemException(
nameof(HelpDisplayStrings.InvalidModuleName),
StringUtil.Format(HelpDisplayStrings.InvalidModuleName, module.Name),
ErrorCategory.InvalidData,
targetObject: null,
innerException: null));
}

return;
}

var keyTuple2 = new Tuple<string, Version>(module.Name, module.Version);
if (!helpModules.ContainsKey(keyTuple2))
{
Expand Down
3 changes: 3 additions & 0 deletions src/System.Management.Automation/resources/HelpDisplayStrings.resx
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Expand Up @@ -449,6 +449,9 @@ To update help again, add the Force parameter to your command.</value>
<data name="InvalidHelpInfoUriFormat" xml:space="preserve">
<value>The HelpInfoURI {0} does not start with HTTP.</value>
</data>
<data name="InvalidModuleName" xml:space="preserve">
<value>The module name '{0}' contains invalid characters and cannot be used to save help content.</value>
</data>
<data name="RootElementMustBeHelpItems" xml:space="preserve">
<value>The root level element of the help content must be "helpItems".</value>
</data>
Expand Down
72 changes: 71 additions & 1 deletion test/powershell/engine/Help/UpdatableHelpSystem.Tests.ps1
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Expand Up @@ -259,7 +259,7 @@ function RunSaveHelpTests
} else {
$null
}

if ($saveHelpFolder) {
New-Item $saveHelpFolder -Force -ItemType Directory > $null
}
Expand Down Expand Up @@ -475,3 +475,73 @@ Describe "Validate 'Save-Help -DestinationPath for all PowerShell modules." -Tag
}
RunSaveHelpTests -Tag "Feature"
}

Describe "Validate 'Save-Help -Module' for module with invalid names" -Tags @('Feature', 'RequireAdminOnWindows') {
BeforeAll {
$SavedProgressPreference = $ProgressPreference
$ProgressPreference = "SilentlyContinue"
}
AfterAll {
$ProgressPreference = $SavedProgressPreference
}

Context "Save-Help validates deserialized module names" {
$invalidModuleNames = @(
@{ ModuleName = 'testmodule'; IsValid = $true },
@{ ModuleName = 'test.module'; IsValid = $true },
@{ ModuleName = 'test-module'; IsValid = $true },
@{ ModuleName = 'test_module'; IsValid = $true },
@{ ModuleName = 'test module'; IsValid = $true },
@{ ModuleName = '.'; IsValid = $false },
@{ ModuleName = '..'; IsValid = $false },
@{ ModuleName = '../testmodule'; IsValid = $false },
@{ ModuleName = '..\testmodule'; IsValid = $false },
@{ ModuleName = '/subDir/testmodule'; IsValid = $false },
@{ ModuleName = '\subDir\testmodule'; IsValid = $false },
@{ ModuleName = '/testmodule'; IsValid = $false },
@{ ModuleName = '\testmodule'; IsValid = $false },
@{ ModuleName = 'C:\testmodule'; IsValid = $false },
@{ ModuleName = 'C:/testmodule'; IsValid = $false },
@{ ModuleName = '..\'; IsValid = $false },
## The char ':' is not allowed on Windows, but allowed on Unix platforms.
@{ ModuleName = 'stream:testmodule'; IsValid = !$isWindows })

It "Save-Help should validate module name '<ModuleName>'" -TestCases $invalidModuleNames {
param ($ModuleName, $IsValid)

$root = Join-Path $TestDrive ("savehelp-namevalidation-" + [guid]::NewGuid().ToString('N'))
$dest = Join-Path $root 'dest'
New-Item -ItemType Directory -Path $dest -Force | Out-Null
$destFull = (Get-Item -LiteralPath $dest).FullName

$mod = [pscustomobject]@{
Name = $ModuleName
Guid = [guid]::NewGuid()
Version = [Version]'1.0.0.0'
ModuleBase = $root
HelpInfoUri = 'https://example.invalid/help/'
}
$mod.PSTypeNames.Insert(0, 'Deserialized.System.Management.Automation.PSModuleInfo')

try
{
Save-Help -Module $mod -DestinationPath $dest -Force -UICulture en-US -ErrorAction SilentlyContinue -ErrorVariable err
}
catch { }

if (!$IsValid){
$err.Count | Should -BeGreaterThan 0
$err[0].FullyQualifiedErrorId | Should -Be 'InvalidModuleName,Microsoft.PowerShell.Commands.SaveHelpCommand'
}
else {
$err[0].FullyQualifiedErrorId | Should -Not -Match 'InvalidModuleName,Microsoft.PowerShell.Commands.SaveHelpCommand'
}

$escaped = @(Get-ChildItem -LiteralPath $root -Recurse -File -Force -ErrorAction SilentlyContinue |
Where-Object { -not $_.FullName.StartsWith($destFull, [System.StringComparison]::OrdinalIgnoreCase) })

$escaped.Count | Should -Be 0
}
}
}

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