Flash Player crashing with Firefox Release & Beta

Hi, today I found a Flash Player content that I can reproduce to crash.

Currently tested on two different devices with Flash Player 25.0.0.130 and Flash Player 24.0.0.221.

Windows 10 Build 15048 64-bit

STR:

a) open http://static4.freenet.de/hilfe_touren/outlook_express6/index2.html with Firefox 52 or 53.0b1 (64-bit)

b) if the "Weiter" (=forward) button is visible at the bottom, click on it

c) Flash Player is crashing (sometimes not at the first "Weiter" button, but at the next ones/steps)

Some Crash Signatures:

[@ @0x0 | uxtheme.dll@0x15358] - Firefox 52.0 Crash Report - Report ID: d69cc124-7010-48eb-8423-505182170309

[@ @0x0 | uxtheme.dll@0x15358] - Firefox 53.0b1 Crash Report - Report ID: 6696f0df-7655-4fc8-a052-fe6cd2170309

[@ @0x0 | user32.dll@0x42a4] - Firefox 52.0 Crash Report - Report ID: 72a3fc2e-e84a-4635-a627-73e002170309​

[@ @0x0 | user32.dll@0x42a4] - Firefox 52.0 Crash Report - Report ID: c828e0ff-c0bd-4e09-ac03-5ab462170309

[@ @0x0 | user32.dll@0x42a4] - Firefox 53.0b1 Crash Report - Report ID: 5da934a8-3685-4967-8938-c73fe2170309

[@ @0x0 | user32.dll@0x42a4] - Firefox 52.0 Crash Report - Report ID: 39f01de6-4d5d-4847-b44e-c095f2170309

[@ @0x0 | user32.dll@0x42a4] - Firefox 53.0b1 Crash Report - Report ID: 73e2a104-38bb-4216-b03e-6ee352170309