Apple has published a Q&A (in Chinese and English) on its China regional site which explains its understanding of events and the impact of the XcodeGhost security issue.
It identifies the 25 most popular apps which are known to have been affected, recommending that users update those as soon as possible. Apple promises to keep this page updated with further information as it becomes available.
At present, all the affected apps were provided through Apple’s China region iTunes App Store, and only for iOS devices. There is still no confirmed case in any app offered in any of Apple’s other stores, either outside the China region, or for OS X.
Thanks to John Ribeiro of the IDG News Service on MacWorld for this link.