Dragging and dropping images exposes final URL after redirects
- September 22, 2015
- Mario Gomes
- Firefox, Firefox ESR, Firefox OS, SeaMonkey, Thunderbird
- Fixed in
- Firefox 41
- Firefox ESR 38.3
- Firefox OS 2.5
- SeaMonkey 2.38
- Thunderbird 38.3
Security researcher Mario Gomes reported that when a previously loaded image on a page is drag and dropped into content after a redirect, the redirected URL is available to scripts. This is a violation of the Fetch specification's defined behavior for "Atomic HTTP redirect handling" which states that redirected URLs are not exposed to any APIs. This can allow for information leakage.
In general this flaw cannot be exploited through email in the Thunderbird product because scripting is disabled, but is potentially a risk in browser or browser-like contexts.