Maintainers for gnumach are GNU Hurd Maintainers <debian-hurd@lists.debian.org>.
You may want to refer to the following packages that are part of the same source: gnumach-common, gnumach-dev, gnumach-image-1-486, gnumach-image-1-xen-486, gnumach-image-1.8-486, gnumach-image-1.8-486-dbg, gnumach-image-1.8-xen-486, gnumach-image-1.8-xen-486-dbg.
You might like to refer to the gnumach package page, to the Package Tracking System, or to the source package src:gnumach's bug page.
If you find a bug not listed here, please report it.