Maintainers for libxcb-composite0 are Debian X Strike Force <debian-x@lists.debian.org>.
You may want to refer to the following packages that are part of the same source: libxcb-composite0-dev, libxcb-damage0, libxcb-damage0-dev, libxcb-doc, libxcb-dpms0, libxcb-dpms0-dev, libxcb-dri2-0, libxcb-dri2-0-dev, libxcb-dri3-0, libxcb-dri3-dev, libxcb-glx0, libxcb-glx0-dev, libxcb-present-dev, libxcb-present0, libxcb-randr0, libxcb-randr0-dev, libxcb-record0, libxcb-record0-dev, libxcb-render0, libxcb-render0-dev, libxcb-res0, libxcb-res0-dev, libxcb-screensaver0, libxcb-screensaver0-dev, libxcb-shape0, libxcb-shape0-dev, libxcb-shm0, libxcb-shm0-dev, libxcb-sync-dev, libxcb-sync1, libxcb-xf86dri0, libxcb-xf86dri0-dev, libxcb-xfixes0, libxcb-xfixes0-dev, libxcb-xinerama0, libxcb-xinerama0-dev, libxcb-xinput-dev, libxcb-xinput0, libxcb-xkb-dev, libxcb-xkb1, libxcb-xtest0, libxcb-xtest0-dev, libxcb-xv0, libxcb-xv0-dev, libxcb-xvmc0, libxcb-xvmc0-dev, libxcb1, libxcb1-dev.
You might like to refer to the libxcb-composite0 package page, to the Package Tracking System, or to the source package src:libxcb's bug page.
If you find a bug not listed here, please report it.