If you use the Apple Calendar on your Mac, iPhone or iPad and have Apple’s iCloud email then you may have received a spam invitation in your calendar, Apple is now working on fix for the issue.
When you receive an email on iCloud, Apple automatically scans it for Calendar invites, these are then shown to you in the Calendar and you can choose to decline the invite or add it.
Spammers have been sending Calendar spam for some time, although this has not really been a problem until recently as iCloud Calendar Invites are now sent to the Calendar automatically.
Apple is apparently working on a fix for the issue, although if you do not want to wait until then, you can log into your iCloud account on the web and change some settings.
You will need to go to your iCloud account online and then fo to Calendar Settings, click on the cog icon and then go to Advanced, you can then change your event invite settings to email only, so thse spam notifications will not be added to the Calendar.