Balance security with functionality in model downloader

- Relax overly restrictive filename validation
- Allow spaces, parentheses, brackets in model filenames (common in model names)
- Keep essential security: no path traversal, no hidden files
- Remove strict alphanumeric-only regex that was blocking valid files
- Keep URL validation but remove overly restrictive host whitelist
- Maintain protection against directory traversal attacks
- Still validate file extensions and model types

The downloader now works with real-world model filenames while remaining secure
against path traversal and other attacks.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

app/simple_downloader.py

@@ -23,11 +23,15 @@ class SimpleDownloader:
         task_id = str(uuid.uuid4())
 
         # SECURITY: Validate and sanitize inputs to prevent path traversal
-        # Sanitize model_type to prevent directory traversal
-        model_type = os.path.basename(model_type).replace('..', '').replace('/', '').replace('\\', '')
+        # Sanitize model_type - remove dangerous characters but keep underscores
+        import re
+        model_type = re.sub(r'[./\\]', '', model_type)
+        model_type = model_type.replace('..', '')
 
-        # Sanitize filename to prevent path traversal
-        filename = os.path.basename(filename).replace('..', '')
+        # Sanitize filename - use os.path.basename and remove traversal attempts
+        filename = os.path.basename(filename)
+        if '..' in filename or filename.startswith('.'):
+            raise ValueError("Invalid filename - no hidden files or path traversal")
 
         # Validate filename has allowed extension
         allowed_extensions = ['.safetensors', '.ckpt', '.pt', '.pth', '.bin', '.sft']

server.py

@@ -822,10 +822,11 @@ class PromptServer():
                     if not filename:
                         filename = "model.safetensors"
 
-                # SECURITY: Sanitize filename
+                # SECURITY: Sanitize filename - allow more characters but still safe
                 import os
                 filename = os.path.basename(filename)
-                if not re.match(r'^[a-zA-Z0-9_.-]+$', filename):
+                # Block path traversal attempts but allow spaces, parens, brackets, etc
+                if '..' in filename or '/' in filename or '\\' in filename or filename.startswith('.'):
                     return web.json_response({"error": "Invalid filename format"}, status=400)
 
                 # Create download task (simple_downloader now has additional validation)