Once I upload an image I get a 401 in the console and an Access denied notification, I had similar problems with rocket loader from cloud flare before but on this blog no services are used. On one of the closed issues I red a bug with version 0.7.5 that looks the same but was fixed.
@klaaz0r is this for every image? does the problem persist after a refresh or when using an Incognito session?
Some screenshots of the web inspector console showing the error and the error in the Network tab of web inspector would be useful if you are able to provide them. Thanks!
I have the same problem. Upload new photo in the post is work fine.
Buy if i try to upload a "Blog Logo" in the Admin dashboard, will show "Access Denied."

114.241.24.224 - - [24/May/2016:18:44:27 +0800] "POST /ghost/api/v0.1/uploads/ HTTP/1.1" 401 73 "http://ghost.rathena.cn/ghost/settings/general/" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_5) AppleWebKit/537.36 (KHTML, like Gecko) ghost-desktop/0.4.0 Chrome/47.0.2526.110 Electron/0.36.12 Safari/537.36"
114.241.24.224 - - [24/May/2016:18:45:11 +0800] "POST /ghost/api/v0.1/uploads/ HTTP/1.1" 401 73 "http://ghost.rathena.cn/ghost/settings/general/" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_5) AppleWebKit/537.36 (KHTML, like Gecko) ghost-desktop/0.4.0 Chrome/47.0.2526.110 Electron/0.36.12 Safari/537.36"
I try to run:
chown -R root:root /data/htdocs/ghost
but not working.
Sorry, i restart the Ghost Desktop(Mac), the problem is solved.
Maybe the session is expired (but if really the session is expired, why i can update the post with no problem?)
@kevinansfield it still happens after a refresh / cache clean / cookies
Ahh didn't see we hosted on ghost.io :(

@klaaz0r are you also using Ghost Desktop?
cc @CairoLee if you're having problems with Ghost Desktop that you cannot also reproduce in the web version, you'll need to raise the issue over on the Ghost Desktop repository.
Okay, got it.
Thank you @ErisDS XD
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Sorry, i restart the Ghost Desktop(Mac), the problem is solved.
Maybe the session is expired (but if really the session is expired, why i can update the post with no problem?)