A common method is to heat a nitrile with KOH ~5-10% in 50-50 ethanol-water at 70-105 for 4-16 hrs. I am looking for something without such aggressive media. Recently I found a paper where whole cells were used as a bio-catalist (from Novozyme) but they are not available commercially as far as I know.
Yes, such aggressive conditions are used because in base, you are trying to eliminate amide anion. In order to do so, you need to make the dialkoxide (the dianion of the hydroxide adduct to an amide). However, a feature or problem of hydrolyzing a nitrile to an amide under acidic conditions is that the amide is more basic than a nitrile. It tends to react faster than the nitrile does.
I agree with dicodermolide about using peroxide and base/K2CO3 (if I remember correctly) to effect a Payne reaction (?). If basic it will generate oxygen gas. If less basic, it produces a peroxyimidate which can be used to make epoxides. Because amides are reasonably basic, they can be hydrolyzed more easily with acid. Ammonium ion will be a good leaving group.