EVHasteToday I learned about "side channel attacks", in which identity of a user can be inferred by whether or not they have permission to view an embedded object on a page.
https://www.wired.com/story/web-deanonymization-side-channel-attack-njit/
Bobinas P4G is a social network. It runs on GNU social, version 2.0.1-beta0, available under the GNU Affero General Public License.
All Bobinas P4G content and data are available under the Creative Commons Attribution 3.0 license.