Another day, another slipup by the Internal Revenue Service. 

The incident involves the unwitting exposure of "tens of thousands" of Social Security numbers, according to a recent audit by the independent transparency and public-domain group Public.Resource.org. The identifying numbers were on the Internet for less than 24 hours after being discovered, but the damage was done. And unfortunately, the data-breach concerns some of the most sensitive types of transactions: Those made by nonprofit political groups known as 527s.