Debian Linux - xen - None Ubuntu Linux - oxenstored: Unbounded accumulation of watches: Oxenstored maintains two datastructures about watches; one global trie, and one hashtable tracked per domain. When a xenbus reconnect is requested, watches are not cleared out of the global trie. A guest can cause unbounded memory usage in oxenstored. This can lead to a system-wide DoS. All version of Xen from 4.6 onwards are vulnerable. Only systems using the Ocaml Xenstored implementation are vulnerable. Systems using the C Xenstored implementation are not vulnerable.