HTC One M8, M7, and other Google Play editions receive Android 4.4.3 as HTC posts kernel source
"By now you know Android 4.4.3 is rolling out to a variety of “stock” Android devices. We already told you about the update hitting Motorola devices (X, G, and E) and have received reports of the update arriving for the both the Samsung Galaxy S4 Google Play edition, and HTC One (M7).
Without wasting any time, HTC is now posting the kernel source for, not only the HTC One (M7), but the HTC One M8 as well. This means the M8 should be joining the party any minute now (along with other GPe devices). You can find links to the source code via the link below."