diff --git a/backend/open_webui/models/access_grants.py b/backend/open_webui/models/access_grants.py
index 49cb83a180..57623532f1 100644
--- a/backend/open_webui/models/access_grants.py
+++ b/backend/open_webui/models/access_grants.py
@@ -515,6 +515,22 @@ class AccessGrantsTable:
             grants = result.scalars().all()
             return [AccessGrantModel.model_validate(g) for g in grants]
 
+    async def get_grants_by_group_id(
+        self,
+        group_id: str,
+        db: Optional[AsyncSession] = None,
+    ) -> list[AccessGrantModel]:
+        """Get all grants given to a specific group."""
+        async with get_async_db_context(db) as db:
+            result = await db.execute(
+                select(AccessGrant).filter_by(
+                    principal_type=PRINCIPAL_TYPE_GROUP,
+                    principal_id=group_id,
+                )
+            )
+            grants = result.scalars().all()
+            return [AccessGrantModel.model_validate(g) for g in grants]
+
     async def get_grants_by_resources(
         self,
         resource_type: str,
diff --git a/backend/open_webui/routers/auths.py b/backend/open_webui/routers/auths.py
index 0ca2f518f8..b31dd62b5e 100644
--- a/backend/open_webui/routers/auths.py
+++ b/backend/open_webui/routers/auths.py
@@ -60,6 +60,7 @@ from open_webui.models.users import (
     Users,
     UserStatus,
 )
+from open_webui.socket.main import leave_group_rooms_for_users
 from open_webui.utils.access_control import get_permissions, has_permission
 from open_webui.utils.auth import (
     create_api_key,
@@ -695,7 +696,13 @@ async def ldap_auth(
                     try:
                         if ENABLE_LDAP_GROUP_CREATION:
                             await Groups.create_groups_by_group_names(user.id, user_groups, db=db)
+                        previous_group_ids = {
+                            group.id for group in await Groups.get_groups_by_member_id(user.id, db=db)
+                        }
                         await Groups.sync_groups_by_group_names(user.id, user_groups, db=db)
+                        current_group_ids = {group.id for group in await Groups.get_groups_by_member_id(user.id, db=db)}
+                        for group_id in previous_group_ids - current_group_ids:
+                            await leave_group_rooms_for_users(group_id, [user.id])
                         log.info('Successfully synced groups for user %s: %s', user.id, user_groups)
                     except Exception as e:
                         log.error(f'Failed to sync groups for user {user.id}: {e}')
@@ -766,7 +773,11 @@ async def signin(
                 group_names = [name.strip() for name in group_names if name.strip()]
 
                 if group_names:
+                    previous_group_ids = {group.id for group in await Groups.get_groups_by_member_id(user.id, db=db)}
                     await Groups.sync_groups_by_group_names(user.id, group_names, db=db)
+                    current_group_ids = {group.id for group in await Groups.get_groups_by_member_id(user.id, db=db)}
+                    for group_id in previous_group_ids - current_group_ids:
+                        await leave_group_rooms_for_users(group_id, [user.id])
 
             if WEBUI_AUTH_TRUSTED_ROLE_HEADER:
                 trusted_role = request.headers.get(WEBUI_AUTH_TRUSTED_ROLE_HEADER, '').lower().strip()
diff --git a/backend/open_webui/routers/groups.py b/backend/open_webui/routers/groups.py
index 4970666b61..4e5279da36 100755
--- a/backend/open_webui/routers/groups.py
+++ b/backend/open_webui/routers/groups.py
@@ -21,6 +21,7 @@ from open_webui.models.knowledge import Knowledges
 from open_webui.models.models import Models
 from open_webui.models.tools import Tools
 from open_webui.models.users import UserInfoResponse, Users
+from open_webui.socket.main import leave_group_rooms_for_users
 from open_webui.utils.auth import get_admin_user, get_verified_user
 from sqlalchemy.ext.asyncio import AsyncSession
 
@@ -270,6 +271,7 @@ async def remove_users_from_group(
     try:
         group = await Groups.remove_users_from_group(id, form_data.user_ids, db=db)
         if group:
+            await leave_group_rooms_for_users(id, form_data.user_ids)
             await publish_event(
                 request,
                 EVENTS.GROUP_MEMBER_REMOVED,
@@ -306,8 +308,10 @@ async def delete_group_by_id(
     request: Request, id: str, user=Depends(get_admin_user), db: AsyncSession = Depends(get_async_session)
 ):
     try:
+        user_ids = await Groups.get_group_user_ids_by_id(id, db=db)
         result = await Groups.delete_group_by_id(id, db=db)
         if result:
+            await leave_group_rooms_for_users(id, user_ids)
             await publish_event(
                 request,
                 EVENTS.GROUP_DELETED,
diff --git a/backend/open_webui/routers/scim.py b/backend/open_webui/routers/scim.py
index a2d093dba8..7ac7724fcf 100644
--- a/backend/open_webui/routers/scim.py
+++ b/backend/open_webui/routers/scim.py
@@ -21,6 +21,7 @@ from open_webui.env import SCIM_AUTH_PROVIDER
 from open_webui.internal.db import get_async_session
 from open_webui.models.groups import GroupModel, Groups
 from open_webui.models.users import UserModel, Users
+from open_webui.socket.main import leave_group_rooms_for_users
 from open_webui.utils.auth import (
     decode_token,
     get_admin_user,
@@ -1064,6 +1065,7 @@ async def update_group(
             data={'member_ids': added_member_ids, 'count': len(added_member_ids)},
         )
     if removed_member_ids:
+        await leave_group_rooms_for_users(group_id, removed_member_ids)
         await publish_event(
             request,
             EVENTS.GROUP_MEMBER_REMOVED,
@@ -1156,6 +1158,7 @@ async def patch_group(
             data={'member_ids': sorted(set(added_member_ids)), 'count': len(set(added_member_ids))},
         )
     if removed_member_ids:
+        await leave_group_rooms_for_users(group_id, removed_member_ids)
         await publish_event(
             request,
             EVENTS.GROUP_MEMBER_REMOVED,
@@ -1182,12 +1185,14 @@ async def delete_group(
             detail=f'Group {group_id} not found',
         )
 
+    member_ids = await Groups.get_group_user_ids_by_id(group_id, db=db)
     success = await Groups.delete_group_by_id(group_id, db=db)
     if not success:
         raise HTTPException(
             status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
             detail='Failed to delete group',
         )
+    await leave_group_rooms_for_users(group_id, member_ids)
 
     await publish_event(
         request,
diff --git a/backend/open_webui/socket/main.py b/backend/open_webui/socket/main.py
index dbfb0f417d..a8bca872e7 100644
--- a/backend/open_webui/socket/main.py
+++ b/backend/open_webui/socket/main.py
@@ -38,6 +38,7 @@ from open_webui.models.channels import Channels
 from open_webui.models.chats import Chats
 from open_webui.models.config import Config
 from open_webui.models.folders import Folders
+from open_webui.models.groups import Groups
 from open_webui.models.notes import Notes, NoteUpdateForm
 from open_webui.models.users import UserNameResponse, Users
 from open_webui.socket.redis_room_channels import AsyncRedisRoomChannelManager
@@ -414,6 +415,44 @@ async def leave_room_for_users(room: str, user_ids: list[str]):
             log.debug('Failed to make session %s leave room %s: %s', sid, room, e)
 
 
+async def leave_group_rooms_for_users(group_id: str, user_ids: list[str]):
+    """Make users leave the note and channel rooms they could only read through a group."""
+    users = await Users.get_users_by_user_ids(user_ids)
+    non_admin_user_ids = [user.id for user in users if user.role != 'admin']
+    group_ids_by_user_id = {
+        user_id: {group.id for group in groups}
+        for user_id, groups in (await Groups.get_groups_by_member_ids(non_admin_user_ids)).items()
+    }
+
+    for grant in await AccessGrants.get_grants_by_group_id(group_id):
+        if grant.permission != 'read':
+            continue
+        if grant.resource_type == 'note':
+            resource = await Notes.get_note_by_id(grant.resource_id)
+            rooms = [f'note:{grant.resource_id}', f'doc_note:{grant.resource_id}']
+        elif grant.resource_type == 'channel':
+            resource = await Channels.get_channel_by_id(grant.resource_id)
+            # Group and DM channels use membership instead of access grants.
+            if resource and resource.type in ['group', 'dm']:
+                continue
+            rooms = [f'channel:{grant.resource_id}']
+        else:
+            continue
+        if not resource:
+            continue
+
+        revoked_user_ids = [
+            user_id
+            for user_id in non_admin_user_ids
+            if user_id != resource.user_id
+            and not await AccessGrants.has_access(
+                user_id, grant.resource_type, grant.resource_id, user_group_ids=group_ids_by_user_id[user_id]
+            )
+        ]
+        for room in rooms:
+            await leave_room_for_users(room, revoked_user_ids)
+
+
 async def disconnect_user_sessions(user_id: str):
     """Disconnect all Socket.IO sessions belonging to a user.
 
diff --git a/backend/open_webui/utils/oauth.py b/backend/open_webui/utils/oauth.py
index 061737a35b..bcfde8cc18 100644
--- a/backend/open_webui/utils/oauth.py
+++ b/backend/open_webui/utils/oauth.py
@@ -83,6 +83,7 @@ from open_webui.models.groups import GroupForm, GroupModel, Groups, GroupUpdateF
 from open_webui.models.oauth_sessions import OAuthSessions
 from open_webui.models.users import Users
 from open_webui.retrieval.web.utils import get_ssrf_safe_session, validate_url
+from open_webui.socket.main import leave_group_rooms_for_users
 from open_webui.utils.auth import (
     create_token,
     get_password_hash,
@@ -1746,6 +1747,7 @@ class OAuthManager:
                 # Remove group from user
                 log.debug('Removing user from group %s as it is no longer in their oauth groups', group_model.name)
                 if await Groups.remove_users_from_group(group_model.id, [user.id], db=db):
+                    await leave_group_rooms_for_users(group_model.id, [user.id])
                     await publish_event(
                         request,
                         EVENTS.GROUP_MEMBER_REMOVED,