Details of HTC's upcoming flagship smartphone have been running around the rumor mill lately. Apart from what has already been known about it, a recent tip claimed that the device will launch sporting the next-gen Android OS.

According to a source familiar with HTC, the forthcoming HTC One A9 will run on the Android 6.0 Marshmallow straight out the box.

A tipster that goes by the alias @LlabTooFeR took claimed on Twitter that aside from having a built-in Android 6.0 Marshmallow OS, fans can grab hold of the HTC One A9 either in October or November.

Only time can tell whether or not the information is accurate. If proven true, the HTC One A9 will have the distinction of being be one of the inaugural non-Nexus devices to run on the Android 6.0 Marshmallow straight out the box.

As for the device's rumored specs, the HTC One A9 will come with a six-inch 1440 x 2560 QHD display, a 10-core MediaTek Helio X20 processor, an IP certification and 4GB of RAM. It is said to have an all-metal build with a 2.5D curved glass design.

PhoneArena earlier reported that the upcoming flagship will be available in two color variants namely Tyrant Gold and Dark Gray. The device will retail anywhere between $470 and $626.

HTC received flak over the unveiling of its Desire 728 smartphone last week since fans thought the Taiwanese mobile manufacturer was referring to the HTC One A9.

The confusion had left anxious fans hanging, although a prior report has rekindled talks about the arrival of the HTC One A9.

Chinese website ePrice via G for Games reported of a teaser that hinted at an HTC press event this Sept 29. HTC will presumably unveil two new flagship smartphones. However, the identity of the devices has yet to be confirmed.

Needless to say, HTC will enrage its fans if the highly anticipated HTC One A9 won't be a part of the duo. The other device rumored to be showcased during the event is the third generation HTC Butterfly.

According to the specs sheet from Compu Bench, the HTC Butterfly 3 will have a 5.1-inch QHD touchscreen display, 3 GB of RAM and 32 GB of internal memory. It will be fitted with a 20-megapixel rear camera with LED flash and a 13-megapixel front-facing unit.

HTC Butterfly 3 will run on the Android 5.0.2 straight out the box and will be powered by Qualcomm's 1.9 GHz 8-core Snapdragon 810 chipset. The said chipset consists of four Cortex-A57 high-performance cores and four Cortex-A53 power-saving cores.