Afghanistan doesn’t allow dual citizenship. There is no Article under the constitution that address the concept of dual citizenship. But after doing some digging I found an old translated constitution (Article 15) of the Islamic Emirate of Afghanistan from Refworld by the UNHCR . Inside of the document it states that it takes 5 years of living Afghanistan to get citizenship and it says dual is not permitted (Article 7). Going back to the 1936 constitution (Article 9) it also states 5 years as well.
Descent, Naturalization, Marriage – There is nothing labeled in the 2004 Constitution
Exception – Under the ICIRR (a state based coalition for refugee rights) “if citizens of Afghanistan who fled the country due to violence and political instability and have since acquired a foreign citizenship, still “unofficially” retain Afghan citizenship. This allows these individuals to maintain the possibility of returning to Afghanistan as Afghan citizens without losing their newly acquired foreign citizenship.”
Office Officials- There is some mention in the 2004 Constitution that individuals holding office cannot have dual citizenship.
Updated March 2016.