Synapse Matrix has a partial room state leak via Sliding Sync

Impact The Sliding Sync feature on Synapse versions between 1.113.0rc1 and 1.120.0 can leak partial room state changes to users no longer in a room. Non-state events, like messages, are unaffected. Patches Synapse version 1.120.1 fixes the problem. Workarounds Disable Sliding Sync. References...