diff --git a/backend/open_webui/retrieval/utils.py b/backend/open_webui/retrieval/utils.py
index 98e15d38e8..13f75175ea 100644
--- a/backend/open_webui/retrieval/utils.py
+++ b/backend/open_webui/retrieval/utils.py
@@ -47,6 +47,7 @@ from open_webui.retrieval.external import retrieve_external_knowledge
 from open_webui.retrieval.vector.factory import VECTOR_DB_CLIENT
 from open_webui.retrieval.vector.main import GetResult, SearchResult
 from open_webui.retrieval.web.utils import get_web_loader
+from open_webui.utils.access_control.chats import has_chat_read_access
 from open_webui.utils.access_control.files import get_owner_accessible_folder_files, has_access_to_file
 from open_webui.utils.access_control.folders import has_folder_access
 from open_webui.utils.headers import include_user_info_headers
@@ -1417,7 +1418,7 @@ async def get_sources_from_items(
             # Chat Attached
             chat = await Chats.get_chat_by_id(item.get('id'))
 
-            if chat and (user.role == 'admin' or chat.user_id == user.id):
+            if chat and await has_chat_read_access(user.id, user.role, chat):
                 messages_map = chat.chat.get('history', {}).get('messages', {})
                 message_id = chat.chat.get('history', {}).get('currentId')
 
diff --git a/backend/open_webui/utils/access_control/chats.py b/backend/open_webui/utils/access_control/chats.py
new file mode 100644
index 0000000000..c082e59b14
--- /dev/null
+++ b/backend/open_webui/utils/access_control/chats.py
@@ -0,0 +1,31 @@
+from typing import Optional
+
+from open_webui.models.access_grants import AccessGrants
+from open_webui.models.chats import ChatModel
+from open_webui.models.folders import Folders
+from open_webui.utils.access_control.folders import has_folder_access
+from sqlalchemy.ext.asyncio import AsyncSession
+
+
+async def has_chat_read_access(
+    user_id: str, user_role: str, chat: ChatModel, db: Optional[AsyncSession] = None
+) -> bool:
+    """Check if a user can read a chat via ownership, admin role, an explicit share grant, or a shared folder."""
+    if user_role == 'admin' or chat.user_id == user_id:
+        return True
+
+    if await AccessGrants.has_access(
+        user_id=user_id,
+        resource_type='shared_chat',
+        resource_id=chat.id,
+        permission='read',
+        db=db,
+    ):
+        return True
+
+    if chat.folder_id:
+        folder = await Folders.get_folder_by_id(chat.folder_id, db=db)
+        if folder and await has_folder_access(user_id, folder, 'read', db):
+            return True
+
+    return False