TalkTalk investigates breach after data for sale on hacking forum

A threat actor posted on a hacking forum in January 2025 claiming to sell TalkTalk customer records (alleged ~18.8M records) and published a sample containing names, emails, last-used IPs and phone numbers. TalkTalk says the figure is significantly overstated and no billing/financial information was stored; CSG Ascendon confirmed the data originated on their platform but reported no compromise of CSG systems and that only a single customer's data was impacted. Investigations and containment are ongoing.