Element Web is a Matrix web client built using the Matrix React SDK. Element Web and Element Desktop before version 1.11.112 have insufficient validation of room predecessor links, allowing a remote attacker to attempt to impermanently replace a room's entry in the room list with an unrelated attacker-supplied room. While the effect of this is temporary, it may still confuse users into acting on incorrect assumptions. The issue has been patched and users should upgrade to 1.11.112. A reload/refresh will fix the incorrect room list state, removing the attacker's room and restoring the original room.
In Element Web and Element Desktop, a malicious room can hide an unrelated room and cause it to be left when the malicious room is left