Maintainers for xen are Debian Xen Team <pkg-xen-devel@lists.alioth.debian.org>.
You may want to refer to the following individual bug pages: libxen-4.1, libxen-4.4, libxen-4.8, libxen-dev, libxen-ocaml, libxen-ocaml-dev, libxenstore3.0, xen-docs-4.1, xen-hypervisor-4.1-amd64, xen-hypervisor-4.1-i386, xen-hypervisor-4.4-amd64, xen-hypervisor-4.4-arm64, xen-hypervisor-4.4-armhf, xen-hypervisor-4.8-amd64, xen-hypervisor-4.8-arm64, xen-hypervisor-4.8-armhf, xen-system-amd64, xen-system-arm64, xen-system-armhf, xen-system-i386, xen-utils-4.1, xen-utils-4.4, xen-utils-4.8, xen-utils-common, xenstore-utils.
You might like to refer to the xen package page, or to the Package Tracking System.
If you find a bug not listed here, please report it.