I'm using twentyeleven theme on my site. I also use WP Super Cache. It's been working out well but over the last few weeks I've noticed strange issue with page navigation buttons. For logged in members (who are not served cached files) everything is fine. But when a guy logs out, the next/previous navigation buttons have the following code appended at the end of the URL:
?nsextt=%00'"--></style></script><script>netsparker(0x0000AA)</script>
Because of this code, all attempts to navigate to older posts are redirected to the home page. If I clear the cache, it works fine even when logged out - but only for a few minutes. As soon as cached files are created, the navigation buttons contain the code at the end and all clicks are as a result redirected to the home page.
I have already reinstalled WP (using latest version), reinstalled the theme and reinstalled and reactivated WP Super Cache. Still the same thing is happening. Any idea why it is and how to fix it? Was my site injected with a malicious code or something?
Thanks a lot ;)