Cycling News is definitely the best international source for xc news, but even they struggle to get reports in from all the countries.
acrossthecountry.net is a really good resource if you can decipher some German.
@UKXCnews on twitter seem to be doing a very good job of collating information, too, but they are only just getting started producing their own content.
MarathonMTB.com covers AUS/NZ, and quite a lot of the european XCM races too.
MTBracenews.com is good for western US stuff. cyclingdirt.org is normally up to date with US MTB and CX news, but they haven’t updated for a while (which is a little worrying)
I’d suggest getting a twitter account. Easy to find all the info you need if you follow the right people.