There is a use-after-free that appears to be related to rendering the display based on multiple scripts. A PoC is attached, tested on Windows only. Note the PoC is somewhat unreliable on some browsers, sometimes it needs to render a minute or two in the foreground before crashing. This is related to unreliability in the freed object being reallocated as a value that causes the crash, not unreliability in the underlying bug (it crashes immediately in a debug build of Flash). With enough effort, an attacker could likely trigger the issue immediately.
This bug is subject to a 90 day disclosure deadline. If 90 days elapse
without a broadly available patch, then the bug report will automatically
become visible to the public.
Status: Fixed