A new property was added to 'server.properties':

# Setting this to true means that the WebDav XML servlets for attachments, calendar, contacts and tasks will be disabled.
# On requests to these servlets a service-not-available (503) response will be sent. See webdav-disabled-message.txt
# to customize the detailed error message that will be sent.
com.openexchange.webdav.disabled=false