Stop apt-get from trying to downgrade nginx on Debian Wheezy

Hi,

For some reasons, apt-get is trying to install an older version of the nginx version currently installed. I never had a case like this and i'd like to know how to not have this kind of case appearing.
I've the latest stable version for my system available afaik aka v1.8.1, and the packages apt-get wants to upgrade are nginx-common (1.2.1-2.2+wheezy4) and nginx-full (1.2.1-2.2+wheezy4_amd64). I think it's related to a recent update on security.debian.org depository : https://www.debian.org/security/2016/dsa-3473.

If needed, my sources.list is :

deb http://debian.mirrors.ovh.net/debian/ wheezy main
deb-src http://debian.mirrors.ovh.net/debian/ wheezy main

deb http://security.debian.org/ wheezy/updates main
deb-src http://security.debian.org/ wheezy/updates main

deb http://nginx.org/packages/debian/ wheezy nginx
deb-src http://nginx.org/packages/debian/ wheezy nginx

#deb http://packages.dotdeb.org wheezy all
#deb-src http://packages.dotdeb.org wheezy all

deb http://packages.dotdeb.org wheezy-php56 all
deb-src http://packages.dotdeb.org wheezy-php56 all

Thanks in advance.