Criminals recently gained access to the customer account details of 1,827 Vodafone UK subscribers, the mobile network confirmed.
Vodafone said the attackers obtained e-mail addresses and passwords from an unknown external source, and that its systems were not compromised.
Criminals got customer names, their mobile numbers, bank sort codes, and the last 4 digits of their bank accounts.
No credit or debit card information was leaked, and Vodafone said the hackers did not get any information that would let them access subscriber bank accounts.
It warned that the information does leave the 1,827 affected customers open to fraud and phishing attempts, though.
Following the attack on Vodafone, there were rumours that Vodacom had been the victim of an attack as well.
The executive head of corporate affairs at Vodacom Tshepo Ramodibe said Vodacom was not hacked, though, and that the 1,827 affected clients were Vodafone UK subscribers only.