Mozilla Gecko before 5.0, as used in Firefox before 5.0 and Thunderbird before 5.0, does not block use of a cross-domain image as a WebGL texture, which allows remote attackers to obtain approximate copies of arbitrary images via a timing attack involving a crafted WebGL fragment shader.
lists.opensuse.org/opensuse-security-announce/2011-07/msg00001.html
lists.whatwg.org/pipermail/whatwg-whatwg.org/2011-March/030882.html
www.contextis.co.uk/resources/blog/webgl/
www.mozilla.org/security/announce/2011/mfsa2011-25.html
bugzilla.mozilla.org/show_bug.cgi?id=655987
bugzilla.mozilla.org/show_bug.cgi?id=656277
bugzilla.mozilla.org/show_bug.cgi?id=659349
developer.mozilla.org/en/WebGL/Cross-Domain_Textures
hacks.mozilla.org/2011/06/cross-domain-webgl-textures-disabled-in-firefox-5/
oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A14221