diff --git a/changelog.d/6884.feature b/changelog.d/6884.feature
new file mode 100644
index 0000000000000000000000000000000000000000..4f6b9630b821a7773f26acef8832e8dca0d88cfa
--- /dev/null
+++ b/changelog.d/6884.feature
@@ -0,0 +1 @@
+Filter out m.room.aliases from /sync state blocks until a full fix lands.
diff --git a/synapse/handlers/sync.py b/synapse/handlers/sync.py
index cd95f85e3f5ba073a316f038393f29da3cf4cac1..2b62fd83fd044a46ca15b5334a253b671e3f3b8d 100644
--- a/synapse/handlers/sync.py
+++ b/synapse/handlers/sync.py
@@ -883,6 +883,7 @@ class SyncHandler(object):
             for e in sync_config.filter_collection.filter_room_state(
                 list(state.values())
             )
+            if e.type != EventTypes.Aliases  # until MSC2261 or alternative solution
         }
 
     async def unread_notifs_for_room_id(self, room_id, sync_config):