Russia is not an arms supplier for the Taliban, but the US is
Except of course the AK-47 is the most common combat rifle on the planet, and Afghanistan has been awash in them since at least the early 1980s when the US flooded the country with Soviet-made arms it purchased from Egypt.
In fact, using CNN's logic there is far more proof that the US is arming the Taliban. At this point in time, the Taliban are awash in state of the art US-made weapons. They're packing the M4 and M16 standard US rifles issued to regular US infantry, the FN SCAR rifle in use by US Special Forces, and besides that, night vision optics, laser scopes, and even up-armored Humvees, which are a Taliban favorite for their suicide car bomb attacks.
This US-made gear is new, and had been brought into country by the US itself. Actually, the US can not account for 700,000 firearms provided to Iraq and Afghanistan since 2002.
It is rather comical to see US generals and the pro-government media try to pin the blame for the US inability to win in Afghanistan on mythical Russian arms shipments when the US is itself a massive, indirect supplier of arms to the Taliban.
Moscow is not supplying the Taliban for a variety of very good reasons, including the fact that it doesn't much like the group. It actually prefers the Kabul government installed by the US, albeit it fears the US-picked regime can not guarantee stability.
That said if Russia, or anyone else, were to begin supplying the Taliban would that be so bad? For sure their social politics are horrible (not that Kabul is far better), but it is undeniable that they're fighting against a foreign occupation. In the European tradition guerrilla resistance to occupation is lauded regardless of the politics of the fighter doing the resisting.