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Mozilla Foundation Security Advisory 2013-12

Title: Buffer overflow in Javascript string concatenation
Impact: Critical
Announced: January 8, 2013
Reporter: pa_kt
Products: Firefox, Thunderbird, SeaMonkey

Fixed in: Firefox 18.0
  Firefox ESR 10.0.12
  Firefox ESR 17.0.2
  Thunderbird 17.0.2
  Thunderbird ESR 10.0.12
  Thunderbird ESR 17.0.2
  SeaMonkey 2.15


Security researcher pa_kt reported a flaw via TippingPoint's Zero Day Initiative that an integer overflow is possible when calculating the length for a Javascript string concatenation, which is then used for memory allocation. This results in a buffer overflow, leading to a potentially exploitable memory corruption.

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.