diff --git a/vendor/magento/module-deploy/Collector/Collector.php b/vendor/magento/module-deploy/Collector/Collector.php
index b09001a7ac0..441d165f679 100644
--- a/vendor/magento/module-deploy/Collector/Collector.php
+++ b/vendor/magento/module-deploy/Collector/Collector.php
@@ -93,6 +93,9 @@ class Collector implements CollectorInterface
                 if ($file->getModule() && !$this->moduleManager->isEnabled($file->getModule())) {
                     continue;
                 }
+                if (!$file->getFileName()) {
+                    continue;
+                }
                 $file->setDeployedFileName($this->fileNameResolver->resolve($file->getFileName()));
                 $params = $this->getParams($file);
                 $packagePath = "{$params['area']}/{$params['theme']}/{$params['locale']}";
diff --git a/vendor/magento/module-deploy/Package/Processor/PreProcessor/Css.php b/vendor/magento/module-deploy/Package/Processor/PreProcessor/Css.php
index 42775a2e2f6..6d0ef0404db 100644
--- a/vendor/magento/module-deploy/Package/Processor/PreProcessor/Css.php
+++ b/vendor/magento/module-deploy/Package/Processor/PreProcessor/Css.php
@@ -120,6 +120,20 @@ class Css implements ProcessorInterface
         return false;
     }
 
+    /**
+     * See if given path is local or remote URL
+     *
+     * @param string $path
+     * @return bool
+     */
+    private function isLocal(string $path): bool
+    {
+        $pattern = '{^(file://(?!//)|/(?!/)|/?[a-z]:[\\\\/]|\.\.[\\\\/]|[a-z0-9_.-]+[\\\\/])}i';
+        $result = preg_match($pattern, $path);
+
+        return is_int($result) ? (bool) $result : true;
+    }
+
     /**
      * Build map file
      *
@@ -135,13 +149,22 @@ class Css implements ProcessorInterface
             $imports = [];
             $this->map[$fullPath] = [];
 
-            $content = $this->staticDir->readFile($this->minification->addMinifiedSign($fullPath));
+            $tmpFilename = $this->minification->addMinifiedSign($fullPath);
+            if ($this->staticDir->isReadable($tmpFilename)) {
+                $content = $this->staticDir->readFile($tmpFilename);
+            } else {
+                $content = '';
+            }
 
             $callback = function ($matchContent) use ($packagePath, $filePath, & $imports) {
-                $importRelPath = $this->normalize(pathinfo($filePath, PATHINFO_DIRNAME) . '/' . $matchContent['path']);
-                $imports[$importRelPath] = $this->normalize(
-                    $packagePath . '/' . pathinfo($filePath, PATHINFO_DIRNAME) . '/' . $matchContent['path']
-                );
+                if ($this->isLocal($matchContent['path'])) {
+                    $importRelPath = $this->normalize(
+                        pathinfo($filePath, PATHINFO_DIRNAME) . '/' . $matchContent['path']
+                    );
+                    $imports[$importRelPath] = $this->normalize(
+                        $packagePath . '/' . pathinfo($filePath, PATHINFO_DIRNAME) . '/' . $matchContent['path']
+                    );
+                }
             };
             preg_replace_callback(Import::REPLACE_PATTERN, $callback, $content);
 
diff --git a/vendor/magento/module-deploy/Package/Processor/PreProcessor/Less.php b/vendor/magento/module-deploy/Package/Processor/PreProcessor/Less.php
index b5fe0c78640..7f6db14ae02 100644
--- a/vendor/magento/module-deploy/Package/Processor/PreProcessor/Less.php
+++ b/vendor/magento/module-deploy/Package/Processor/PreProcessor/Less.php
@@ -58,6 +58,11 @@ class Less implements ProcessorInterface
      */
     private $map = [];
 
+    /**
+     * @var array
+     */
+    private $pFileCache = [];
+
     /**
      * Less constructor
      *
@@ -131,6 +136,7 @@ class Less implements ProcessorInterface
         $currentPackageFiles = array_merge($package->getFilesByType('less'), $package->getFilesByType('css'));
 
         foreach ($currentPackageFiles as $file) {
+            $this->pFileCache = [];
             if ($this->inParentFiles($file->getDeployedFileName(), $parentFile->getFileName(), $map)) {
                 return true;
             }
@@ -151,6 +157,10 @@ class Less implements ProcessorInterface
                 return true;
             } else {
                 foreach ($map[$parentFile] as $pFile) {
+                    if (in_array($pFile, $this->pFileCache)) {
+                        continue;
+                    }
+                    $this->pFileCache[] = $pFile;
                     return $this->inParentFiles($fileName, $pFile, $map);
                 }
             }