403 Forbidden Facebook Thumbnail

Hello,
When I share some of my posts on Facebook, they either don’t show a thumbnail or show 403 Forbidden Error thumbnail.

This happens to some of my posts. I either copy and paste the link on my FB wall or share the post by clicking on the “share” button from an installed plugin. In the first case I get no thumbnail. In the second case, I get a 403 Forbidden thumbnail.

I’ve used a variety of plugins and have the same 403 Forbidden error with all of them. So, I am assuming that this is not a plugin problem.

This is one of the posts that presents this problem.
http://dimancherougemag.org/dimanche-rouge-presents-agnes-nedregard-in-argentina-2305-02062014/

I’ve updated WP yesterday and also updated all the plugins.

I thank you in advance for any help with this!