The MyVodafone app is designed for managing the mobile carrier’s account and offers quick access to bills, or active services. It also provides information about call rates in other countries, reward points, promotions, and data plans. The company confirmed the privacy breach saying that it was caused by an error during a planned upgrade of the app. It is unclear how many users had their personal information exposed this way, but some are concerned about how they can know if their details were revealed to others.
Source: https://www.bleepingcomputer.com/news/security/vodafones-mobile-app-briefly-exposed-customer-information/