Facebook has revealed that a software bug exposed the photos of up to 6.8 million users, including pictures they had not posted. It made the announcement a day after hosting its pop-up privacy experience It's Your Facebook in New York's Bryant Park.
Twitter has deleted an estimated 10,000 automated accounts that were posting messages discouraging people from taking part in next week's US mid-term elections.
During the first round of Brazil's presidential election on 7 October, Facebook staff noticed something suspicious on the social network. A story posted to Facebook incorrectly claimed the election was delayed because of protests. The company's data scientists and operations team scrambled to pull down the misinformation before it went viral.