Cross-site Request Leak Report
Firefox v62 (default settings)

To evaluate whether your current browser instance's cookie policies can be bypassed with one of the request mechanisms, simply click on the specific instance you want to test. This will open a new tab, where the test is set up and executed: the test will try to initiate a cross-site request to After a few seconds, you will be redirected back to this page, showing the results of the test.

To analyze the correctness of your browser extension, make sure to mark the checkbox underneath.

Test with cross-site request that should be blocked by easylist.txt:

Request Mechanism


form-GET, meta-refresh, redirect-winloc, status-300, status-301, status-302, status-303, status-307, status-308






after-content, background-image, before-content, border-image-source, cursor, escape-url, import-string, import-url, variables

Response headers

link-prefetch, link-stylesheet

HTML elements

body-background, embed-src, iframe-src, iframe-src-data-svg-image-href, iframe-src-javascript-atob-img-src, iframe-src-javascript-img-src, iframe-srcdoc-img-src, image-src, img-src, img-srcset, input-src, link-apple-touch-icon-precomposed, link-prefetch, link-shortcut-icon, link-stylesheet, object-data, picture-img-srcset, script-src, svg-feimage, svg-image-href, svg-image-xlink-href, svg-rect-cursor, svg-rect-mask, svg-script-href, svg-script-xlink-href, table-background, td-background, video-poster, video-src


event-source-credentials-include, fetch-credentials-include, fetch-GET-credentials-include, fetch-HEAD-credentials-include, fetch-POST-credentials-include, send-beacon, websocket-wss, xhr-get-withCredentials, xhr-head-withCredentials, xhr-post-withCredentials

Service worker

fetch-credentials-include, fetch-GET-credentials-include, fetch-HEAD-credentials-include, fetch-POST-credentials-include, refetch-through-innocent-script


event-source, fetch, fetch-GET, fetch-HEAD, fetch-POST, xhr-delete, xhr-delete-withCredentials, xhr-get, xhr-head, xhr-post, xhr-put, xhr-put-withCredentials


font-face, font-face-fallback, shape-outside

Service worker

fetch, fetch-GET, fetch-HEAD, fetch-POST