diff --git a/apps/api/plane/app/views/asset/v2.py b/apps/api/plane/app/views/asset/v2.py
index 3b6d4dce8bc..6d835f6a225 100644
--- a/apps/api/plane/app/views/asset/v2.py
+++ b/apps/api/plane/app/views/asset/v2.py
@@ -10,6 +10,7 @@
 from django.http import HttpResponseRedirect
 from django.utils import timezone
 from django.db import IntegrityError
+from django.db.models import Q
 
 # Third party imports
 from rest_framework import status
@@ -708,8 +709,19 @@ def post(self, request, slug, project_id, entity_id):
         if not asset_ids:
             return Response({"error": "No asset ids provided."}, status=status.HTTP_400_BAD_REQUEST)
 
-        # get the asset id — scope to the project to prevent cross-project IDOR
-        assets = FileAsset.objects.filter(id__in=asset_ids, workspace__slug=slug, project_id=project_id)
+        # Scope to the requester's own uploads in this workspace, limited to assets that are
+        # either unassociated or already in this project. This endpoint *associates*
+        # freshly-uploaded assets, which are not yet project-scoped (e.g. a cover uploaded
+        # during project creation has project_id=NULL until this call sets it) — so the
+        # earlier project_id=project_id filter 404'd that flow. created_by + the
+        # unassociated-or-same-project bound prevent cross-project/user IDOR (a caller can
+        # only touch their own uploads, cannot move an asset in from another project, and
+        # @allow_permission already scopes them to this project).
+        assets = FileAsset.objects.filter(
+            id__in=asset_ids,
+            workspace__slug=slug,
+            created_by=request.user,
+        ).filter(Q(project_id=project_id) | Q(project_id__isnull=True))
 
         # Get the first asset
         asset = assets.first()
diff --git a/apps/api/plane/utils/path_validator.py b/apps/api/plane/utils/path_validator.py
index ab2e2bae537..2ea71c18f23 100644
--- a/apps/api/plane/utils/path_validator.py
+++ b/apps/api/plane/utils/path_validator.py
@@ -15,8 +15,8 @@ def sanitize_filename(filename):
     """
     Sanitize a filename to prevent path traversal attacks.
 
-    Strips directory components, path traversal sequences, and null bytes
-    from user-supplied filenames used in upload paths and S3 object keys.
+    Strips directory components, path traversal sequences, and control
+    characters from user-supplied filenames used in upload paths and S3 object keys.
 
     Returns None for empty/missing input so callers can still validate
     that a filename was provided.
@@ -24,8 +24,8 @@ def sanitize_filename(filename):
     if not filename or not isinstance(filename, str):
         return None
 
-    # Strip null bytes
-    filename = filename.replace("\x00", "")
+    # Strip ASCII control characters (0-31 and 127), including null bytes
+    filename = "".join(char for char in filename if not (ord(char) < 32 or ord(char) == 127))
 
     # Normalize backslashes so os.path.basename handles Windows-style paths on POSIX
     filename = filename.replace("\\", "/")