Plugin configuration and associated assets such as images are not available to all users, for example using core_v2_siteCustomNavigation

I was looking to setup some centralised navigation links so added a custom navigation property to a plugin 

            var customNavigationProperty = new Property()
            {
                Id = "custom_navigation",
                LabelText = "Custom Navigation",
                DescriptionText = "Allow for global custom navigation",
                DataType = "custom",
                Template = "core_v2_siteCustomNavigation",
                OrderNumber = 1,
                Options = new NameValueCollection
                {
                    { "maxDepth", "2" },
                    { "enableDescriptions", "true" },
                    { "enableAvatars", "true" }
                }
            };

This appeared at first to work as expected and stored the associated avatar files into cfs as below (in this case group avatars)

pluginfiles/{namespace}-Plugins-CorePlugin-custom_5F00_navigation/CX.jpg.jpg

The files are accessible by admin users, but if a regular user tries to access the file they get  403 or access denied page

Is there anywhere we can change the permissions of the files which are copied into this pluginfiles cfs folder ?