diff --git a/backend/open_webui/main.py b/backend/open_webui/main.py
index 1ac8724278..38ac43262c 100644
--- a/backend/open_webui/main.py
+++ b/backend/open_webui/main.py
@@ -1424,7 +1424,7 @@ async def chat_completion(
                             try:
                                 from open_webui.utils.timers import cancel_timers_for_chat
 
-                                await cancel_timers_for_chat(chat_id, 'chat.user_message')
+                                await cancel_timers_for_chat(chat_id, 'chat.user_message', user.id)
                             except Exception:
                                 log.exception('Failed to cancel chat.user_message timers for chat %s', chat_id)
 
diff --git a/backend/open_webui/socket/main.py b/backend/open_webui/socket/main.py
index 691b91f322..e9ebb4d770 100644
--- a/backend/open_webui/socket/main.py
+++ b/backend/open_webui/socket/main.py
@@ -533,11 +533,12 @@ async def chat_events(sid, data):
     event_type = event_data.get('type')
 
     if event_type == 'last_read_at':
-        await Chats.update_chat_last_read_at_by_id(data['chat_id'], user['id'])
+        if not await Chats.update_chat_last_read_at_by_id(data['chat_id'], user['id']):
+            return
         try:
             from open_webui.utils.timers import cancel_timers_for_chat
 
-            await cancel_timers_for_chat(data['chat_id'], 'chat.read')
+            await cancel_timers_for_chat(data['chat_id'], 'chat.read', user['id'])
         except Exception:
             log.exception('Failed to cancel chat.read timers for chat %s', data.get('chat_id'))
 
diff --git a/backend/open_webui/utils/timers.py b/backend/open_webui/utils/timers.py
index 25d98f17be..5500daa21a 100644
--- a/backend/open_webui/utils/timers.py
+++ b/backend/open_webui/utils/timers.py
@@ -199,10 +199,14 @@ async def claim_due_timers(now_ns: int, limit: int = 10) -> list[tuple[str, str]
         return claimed
 
 
-async def cancel_timers_for_chat(parent_chat_id: str, event: Literal['chat.read', 'chat.user_message']) -> None:
+async def cancel_timers_for_chat(
+    parent_chat_id: str, event: Literal['chat.read', 'chat.user_message'], user_id: str
+) -> None:
+    """Owner-scoped: without the user filter, reading a chat cancels every user's timers on it."""
     async with get_async_db() as db:
         result = await db.execute(
             select(Chat)
+            .where(Chat.user_id == user_id)
             .where(Chat.meta['internal'].as_boolean().is_(True))
             .where(Chat.meta['type'].as_string() == 'timer')
             .where(Chat.meta['parent_chat_id'].as_string() == parent_chat_id)