The Swedish book retailer Adlibris (http://www.adlibris.se) has a web service that allows users to retrieve cover images over HTTP and HTTPS via ISBN. No credentials or cookies are required. Halland County library plans to add support (via a system preference) to retrieve this covers. Enabling this will risk data leakage to the store about what titles people search for and which titles they look at. Using HTTPS protects the data from interception by third parties but the second party can see the results in the web logs of the server. Identification of users is possible if the computer used has cookies set for the adlibris.se domain (as well as more sophisticated methods).
There is another bug for this: 8630.
*** This bug has been marked as a duplicate of bug 8630 ***