A reference leak vulnerability exists in the items-view union and subtraction operators of aio-libs/multidict versions 6.7.0 through 6.9.0. This flaw allows a remote client to cause unbounded memory growth by leaking references to key-identity and value objects during certain set operations on items views. The leak occurs because the code fails to release new references created during parsing, leading to unreclaimable memory consumption until the process is terminated.