Download Firefox

Firefox is no longer supported on Windows 8.1 and below.

Please download Firefox ESR (Extended Support Release) to use Firefox.

Firefox is no longer supported on macOS 10.14 and below.

Please download Firefox ESR (Extended Support Release) to use Firefox.

Firefox Privacy Notice

Mozilla Foundation Security Advisory 2015-40

Same-origin bypass through anchor navigation

Announced
March 31, 2015
Reporter
Olli Pettay, Boris Zbarsky
Impact
High
Products
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

Description

Mozilla developer Olli Pettay reported that while investigating Mozilla Foundation Security Advisory 2015-28, he and Mozilla developer Boris Zbarsky found an alternate way to trigger a similar vulnerability. The previously reported flaw used an issue with SVG content navigation to bypass same-origin policy protections to run scripts in a privileged context. This newer variant found that the same flaw could be used during anchor navigation of a page, allowing bypassing of same-origin policy protections.

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.

References