A pedestrian talks on his cell phone while walking past the Verizon Communications Inc. headquarters in New York.

More than 1.5 million Verizon Enterprise customers had their contact information leaked on an underground cybercrime forum this week, according to cybersecurity blogger Brian Krebs.

A security vulnerability, now fixed, provided an opening for the attacker, the business-to-business arm of the mobile and telecom giant told KrebsoOnSecurity. The breach involved basic contact information, not propriety network information, the company told Krebs.