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Mozilla Foundation Security Advisory 2010-42

Title: Cross-origin data disclosure via Web Workers and importScripts
Impact: High
Announced: July 20, 2010
Reporter: Yosuke Hasegawa
Products: Firefox, Thunderbird, SeaMonkey

Fixed in: Firefox 3.6.7
  Firefox 3.5.11
  Thunderbird 3.1.1
  Thunderbird 3.0.6
  SeaMonkey 2.0.6


Security researcher Yosuke Hasegawa reported that the Web Worker method importScripts can read and parse resources from other domains even when the content is not valid JavaScript. This is a violation of the same-origin policy and could be used by an attacker to steal information from other sites.