Reject unsafe plugin package names in installer

1 files changed, 43 insertions, 0 deletions

diff --git a/Emby.Server.Implementations/Updates/InstallationManager.cs b/Emby.Server.Implementations/Updates/InstallationManager.cs
index ef53e3b326..c8a2d98bf4 100644
--- a/Emby.Server.Implementations/Updates/InstallationManager.cs
+++ b/Emby.Server.Implementations/Updates/InstallationManager.cs
@@ -521,9 +521,27 @@ namespace Emby.Server.Implementations.Updates
                 return;
             }
 
+            if (!IsValidPackageDirectoryName(package.Name))
+            {
+                _logger.LogError("Refusing to install package with invalid name {PackageName}.", package.Name);
+                throw new InvalidDataException($"Plugin package name '{package.Name}' is not a valid directory name.");
+            }
+
             // Always override the passed-in target (which is a file) and figure it out again
             string targetDir = Path.Combine(_appPaths.PluginsPath, package.Name);
 
+            var pluginsRoot = Path.TrimEndingDirectorySeparator(Path.GetFullPath(_appPaths.PluginsPath));
+            var resolvedTarget = Path.GetFullPath(targetDir);
+            if (!resolvedTarget.StartsWith(pluginsRoot + Path.DirectorySeparatorChar, StringComparison.OrdinalIgnoreCase))
+            {
+                _logger.LogError(
+                    "Refusing to install package {PackageName}: resolved target {Resolved} is outside plugins directory {Root}.",
+                    package.Name,
+                    resolvedTarget,
+                    pluginsRoot);
+                throw new InvalidDataException($"Plugin package name '{package.Name}' resolves outside the plugins directory.");
+            }
+
             using var response = await _httpClientFactory.CreateClient(NamedClient.Default)
                 .GetAsync(new Uri(package.SourceUrl), cancellationToken).ConfigureAwait(false);
             response.EnsureSuccessStatusCode();
@@ -572,6 +590,31 @@ namespace Emby.Server.Implementations.Updates
             _pluginManager.ImportPluginFrom(targetDir);
         }
 
+        private static bool IsValidPackageDirectoryName(string? name)
+        {
+            if (string.IsNullOrWhiteSpace(name))
+            {
+                return false;
+            }
+
+            if (name.Equals(".", StringComparison.Ordinal) || name.Equals("..", StringComparison.Ordinal))
+            {
+                return false;
+            }
+
+            if (name.Contains('/', StringComparison.Ordinal) || name.Contains('\\', StringComparison.Ordinal))
+            {
+                return false;
+            }
+
+            if (name.AsSpan().IndexOfAny(Path.GetInvalidFileNameChars()) >= 0)
+            {
+                return false;
+            }
+
+            return true;
+        }
+
         private async Task<bool> InstallPackageInternal(InstallationInfo package, CancellationToken cancellationToken)
         {
             LocalPlugin? plugin = _pluginManager.Plugins.FirstOrDefault(p => p.Id.Equals(package.Id) && p.Version.Equals(package.Version))