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Mozilla Foundation Security Advisory 2013-14

Title: Chrome Object Wrapper (COW) bypass through changing prototype
Impact: High
Announced: January 8, 2013
Reporter: Mariusz Mlynski
Products: Firefox, Thunderbird, SeaMonkey

Fixed in: Firefox 18.0
  Firefox ESR 17.0.2
  Thunderbird 17.0.2
  Thunderbird ESR 17.0.2
  SeaMonkey 2.15


Security researcher Mariusz Mlynski reported that it is possible to change the prototype of an object and bypass Chrome Object Wrappers (COW) to gain access to chrome privileged functions. This could allow for arbitrary code execution.

In general these flaws cannot be exploited through email in the Thunderbird and SeaMonkey products because scripting is disabled, but are potentially a risk in browser or browser-like contexts in those products.