Mozilla Foundation Security Advisory 2015-33

resource:// documents can load privileged pages

March 31, 2015
Mariusz Mlynski
Firefox, Firefox ESR, Firefox OS, SeaMonkey, Thunderbird
Fixed in
  • Firefox 37
  • Firefox ESR 31.6
  • Firefox OS 2.2
  • SeaMonkey 2.35
  • Thunderbird 31.6


Security researcher Mariusz Mlynski reported, through HP Zero Day Initiative's Pwn2Own contest, that documents loaded though a resource: URL, such as Mozilla's PDF.js PDF file viewer, were able to subsequently load privileged chrome pages. The privilege restrictions on resource: URLs was handled incorrectly and these restrictions could be bypassed if this flaw was combined with a separate vulnerability allowing for same-origin policy violation, it could be used to run arbitrary code.

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.