Delta Air Lines says customers’ payment information may have been breached in a cyberattack last fall. The airline said yesterday the incident involved (24)7.ai, a chat-services provider used by Delta and other companies. Delta says only “a small subset” of customers were affected, with payment information exposed from Sept. 26 to Oct. 12. It says no other personal details about customers, such as their passport, security or frequent-flyer account information, was affected. The Atlanta-based airline says (24)7.ai informed it of the breach last week. Delta brought in federal law enforcement and forensic teams and confirmed that the unauthorized access was cut off by October. Delta says it will make sure customers aren’t held responsible if their payment cards were used fraudulently. It will create a website today to update customers.