Twitter disclosed an issue in the way the Mozilla Firefox web browser cached data that may have lead to private media shared in direct messages and data downloads being inadvertently stored in the browser’s cache. Twitter says that it has made a change to its platform that will prevent Firefox from caching users’ personal information going forward. The private data stored by Firefox is automatically being removed after the browser s default cache retention period of 7 days is reached, with all the accidentally stored private info also being deleted in the process.
Source: https://www.bleepingcomputer.com/news/security/twitter-reveals-that-firefox-cached-private-data-for-up-to-7-days/