Effeithiodd y digwyddiad ar ddau ddeg chwech o systemau sy'n cael eu lletya'n genedlaethol sy'n rheoli apwyntiadau i gleifion ac sy'n rhannu atgyfeiriadau cleifion, canlyniadau profion, canlyniadau labordai a cheisiadau gan feddygon teulu am brofion. Cafodd system e-bost GIG Cymru ei heffeithio hefyd.
This incident affected twenty-six nationally-hosted systems, including systems which manage appointments and which share patient referrals, tests results, laboratory results and GP test requests. The NHS Wales email system was also impacted.