Hallisey & D’Agostino, LLP Data Breach Exposes Personal Information of Over 16,000 Individuals Hallisey & D’Agostino, LLP, a Connecticut-based public accounting firm, recently disclosed a data breach that compromised the sensitive personal information of 16,683 individuals across the U.S., including 74 in Maine. The firm, headquartered in Wethersfield, detected unusual activity in its network on October 21, 2025, prompting an immediate investigation with external cybersecurity experts. The probe revealed that an unauthorized actor accessed the firm’s systems between September 28 and October 22, 2025, potentially exfiltrating files containing personal data. After a thorough review, completed on March 19, 2026, the firm confirmed the exposure and began notifying affected individuals via written notices on April 17, 2026. The breach has drawn attention from Shamis & Gentile P.A., a class action law firm specializing in data breach cases, which is investigating potential legal action for those impacted. The incident underscores the ongoing risks of cyber threats targeting professional service providers handling sensitive client information.