NEW YORK — Luxury merchant Neiman Marcus confirmed Saturday that thieves stole some of its customers’ payment card information and made unauthorized charges over the holiday season, becoming the second retailer in recent weeks to announce it had fallen victim to a cyber-security attack.

The hacking, coming weeks after Target Corp. revealed its own breach, underscores the increasing challenges that merchants have in thwarting security threats. Neiman Marcus didn’t say whether the breach was related to the massive data theft at Target, but some security experts believe they could be part of the same scam. Nevertheless, the recent security breaches at two major retailers threaten to scare shoppers who worry about the safety of their personal data.