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 key-identity and value objects during certain set operations on dictionary views. The leak occurs because new references are created but not properly released in the first parse loop of these operations. This leads to increasing resident memory usage until the process is terminated.