AT&T discloses a material cybersecurity incident

What the filing says

On April 19, 2024, AT&T Inc. ("AT&T") learned that a threat actor claimed to have unlawfully accessed and copied AT&T call logs. AT&T immediately activated its incident response process to investigate and retained external cybersecurity experts to assist. Based on its investigation, AT&T believes that threat actors unlawfully accessed an AT&T workspace on a third-party cloud platform and, between April 14 and April 25, 2024, exfiltrated files containing AT&T records of customer call and text interactions that occurred between approximately May 1 and October 31, 2022, as well as on January 2, 2023, as described below.