A use-after-free can occur during buffer storage operations within the ANGLE graphics library, used for WebGL content. The buffer storage can be freed while still in use in some circumstances, leading to a potentially exploitable crash. Note: This issue is in "libGLES", which is only in use on Windows. Other operating systems are not affected. This vulnerability affects Firefox < 52 and Thunderbird < 52.
https://www.mozilla.org/security/advisories/mfsa2017-09/
https://www.mozilla.org/security/advisories/mfsa2017-05/
https://bugzilla.mozilla.org/show_bug.cgi?id=1325511