The company said the attacker however did not gain access to Customer Proprietary Network Information (CPNI) or other data.
CPNI is the information that telephone companies collect including the time, date, duration and destination number of each call and the type of network a consumer subscribes to.
Krebs On Security, which first broke the news of the breach, said a member of a underground cybercrime forum had posted a new thread advertising the sale of a database containing the contact information on some 1.5 million customers of Verizon Enterprise.
The vulnerability, which was investigated and fixed, did not leak any data on consumer customers.
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