Ernst & Young Confirms Client Tax Data Breach After Cyberattack on Support Platform

Full text

Ernst & Young confirms breach via a third‑party IT service management platform, exposing client tax data between March 28 and April 12, 2026

Attackers accessed documents tied to tax support tickets; exact scope and affected clients remain undisclosed, with no dark web leaks or group claims so far

EY activated incident response, secured systems, and is offering 24 months of Experian identity monitoring to impacted customers

Ernst & Young (EY) has confirmed suffering a cyberattack in which it lost sensitive customer information, including tax data.

In a data breach notification letter sent to affected individuals, the firm said that on April 23, 2026, it spotted “anomalous activity” within a third-party platform its IT team uses. This is an IT service management platform that helps EY staff support the teams that perform tax-related work for clients. Therefore, the tickets submitted through this platform sometimes also contain documents with client tax information which may have been exposed in the incident.

EY then activated its incident response protocols, bringing in third-party cybersecurity experts, as well as notifying relevant authorities and affected clients.

Free identity theft protection

Further investigation determined that the unnamed threat actors broke in on March 28, 2026 and have, until April 12, been exfiltrating the files. EY did not say exactly which information was pulled, or how many clients were affected. We also don’t know if this only pertains to US clients, or overseas ones, as well. The attackers have, since then, been removed from EY’s virtual premises, and the systems have been secured, the company confirmed.

So far, no hacking groups claimed responsibility for this attack, and the data is yet to surface anywhere on the dark web. EY’s customers should be on the lookout for unsolicited emails, especially those claiming to be from the professional services giant.

To help them stay secure, EY is offering 24 months of free identity monitoring and restoration services through Experian.

Ernst & Young is one of the "Big Four" largest professional services and accounting networks in the world. It is headquartered in London, but operates as a global network of independent members spanning more than 150 countries and employing more than 400,000 people. The company’s core business includes assurance, tax, consulting, and M&A strategy.

Via BleepingComputer