Following the release of firmware update for PlayStation 4, Sony has also released new firmware targeted at its portable PlayStation Vita console. The update version 3.18 improves latest security patches as well as improved stability while using some of the features.
Apparently it fixes the "homebrew" exploit, which allowed running copies of pirated PSP games on the platform. There is no official changelog, so we can't comment on other changes.
PS Vita system software update 3.18 coming soon, improves system software stability during use of some features— PlayStation (@PlayStation) August 7, 2014