diff --git a/backend/open_webui/models/knowledge.py b/backend/open_webui/models/knowledge.py
index 401265a1c6..848232d6f2 100644
--- a/backend/open_webui/models/knowledge.py
+++ b/backend/open_webui/models/knowledge.py
@@ -467,14 +467,22 @@ class KnowledgeTable:
             print('search_knowledge_files error:', e)
             return KnowledgeFileListResponse(items=[], total=0)
 
-    async def check_access_by_user_id(self, id, user_id, permission='write', db: Optional[AsyncSession] = None) -> bool:
+    async def check_access_by_user_id(
+        self,
+        id,
+        user_id,
+        permission='write',
+        db: Optional[AsyncSession] = None,
+        user_group_ids: set[str] | None = None,
+    ) -> bool:
         knowledge = await self.get_knowledge_by_id(id, db=db)
         if not knowledge:
             return False
         if knowledge.user_id == user_id:
             return True
-        user_groups = await Groups.get_groups_by_member_id(user_id, db=db)
-        user_group_ids = {group.id for group in user_groups}
+        if user_group_ids is None:
+            user_groups = await Groups.get_groups_by_member_id(user_id, db=db)
+            user_group_ids = {group.id for group in user_groups}
         return await AccessGrants.has_access(
             user_id=user_id,
             resource_type='knowledge',
diff --git a/backend/open_webui/routers/folders.py b/backend/open_webui/routers/folders.py
index c4ed8d0d4d..9a6ff1c4df 100644
--- a/backend/open_webui/routers/folders.py
+++ b/backend/open_webui/routers/folders.py
@@ -99,6 +99,10 @@ async def get_folders(
     folders = await Folders.get_folders_by_user_id(user.id, db=db)
     folder_ids = {folder.id for folder in folders}
 
+    user_group_ids = None
+    if user.role != 'admin' and any(folder.data and 'files' in folder.data for folder in folders):
+        user_group_ids = {group.id for group in await Groups.get_groups_by_member_id(user.id, db=db)}
+
     # Verify folder data integrity
     folder_list = []
     for folder in folders:
@@ -106,7 +110,9 @@ async def get_folders(
             folder = await Folders.update_folder_parent_id_by_id_and_user_id(folder.id, user.id, None, db=db)
 
         if folder.data and 'files' in folder.data:
-            accessible_files = await get_accessible_folder_files(folder.data['files'], user, db=db)
+            accessible_files = await get_accessible_folder_files(
+                folder.data['files'], user, db=db, user_group_ids=user_group_ids
+            )
             if len(accessible_files) != len(folder.data.get('files', [])):
                 folder.data['files'] = accessible_files
                 await Folders.update_folder_by_id_and_user_id(
diff --git a/backend/open_webui/utils/access_control/files.py b/backend/open_webui/utils/access_control/files.py
index 5d192db603..efc8b11222 100644
--- a/backend/open_webui/utils/access_control/files.py
+++ b/backend/open_webui/utils/access_control/files.py
@@ -128,6 +128,7 @@ async def get_accessible_folder_files(
     entries: list[dict] | None,
     user: UserModel,
     db: AsyncSession | None = None,
+    user_group_ids: set[str] | None = None,
 ) -> list[dict]:
     """Filter folder.data['files'] entries to those the caller can read.
 
@@ -144,8 +145,8 @@ async def get_accessible_folder_files(
     if user.role == 'admin':
         return entries
 
-    # One group-membership fetch for the whole folder listing
-    user_group_ids = {group.id for group in await Groups.get_groups_by_member_id(user.id, db=db)}
+    if user_group_ids is None:
+        user_group_ids = {group.id for group in await Groups.get_groups_by_member_id(user.id, db=db)}
 
     accessible: list[dict] = []
     for entry in entries:
@@ -155,7 +156,9 @@ async def get_accessible_folder_files(
             if await has_access_to_file(entry_id, 'read', user, db=db, user_group_ids=user_group_ids):
                 accessible.append(entry)
         elif entry_type == 'collection':
-            if await Knowledges.check_access_by_user_id(entry_id, user.id, 'read', db=db):
+            if await Knowledges.check_access_by_user_id(
+                entry_id, user.id, 'read', db=db, user_group_ids=user_group_ids
+            ):
                 accessible.append(entry)
         elif entry_type == 'note':
             # Owner has no self-grant (notes are private by default), so check ownership too.
@@ -169,6 +172,7 @@ async def get_accessible_folder_files(
                     resource_type='note',
                     resource_id=entry_id,
                     permission='read',
+                    user_group_ids=user_group_ids,
                     db=db,
                 )
             ):