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Mozilla Foundation Security Advisory 2015-94

Use-after-free when resizing canvas element during restyling

Announced
August 27, 2015
Reporter
Jean-Max Reymond
Impact
Critical
Products
Firefox, Firefox ESR, SeaMonkey
Fixed in
  • Firefox 40.0.3
  • Firefox ESR 38.2.1
  • SeaMonkey 2.35

Description

Mozilla community member Jean-Max Reymond discovered a use-after-free vulnerability with a <canvas> element on a page. This occurs when a resize event is triggered in concert with style changes but the canvas references have been recreated in the meantime, destroying the originally referenced context. This results in an exploitable crash.

Ucha Gobejishvili, working with HP's Zero Day Initiative, subsequently reported this same issue.

References