Ernst & Young reveals data breach after support system attack

Ernst & Young confirms breach via third-party IT service management platform, exposing clients’ tax data between March 28 and April 12, 2026
The attackers accessed documents linked to tax support tickets; The exact scope and customers affected remain undisclosed, with no dark web leaks or group claims as of yet.
EY activated incident response, secured systems and is offering 24 months of Experian identity monitoring to affected customers.

Ernst & Young (EY) has confirmed that it suffered a cyber attack in which it lost sensitive client information, including tax data.

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

EY then activated its incident response protocols, engaged external cybersecurity experts, and notified relevant authorities and affected clients.

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Further investigation determined that the anonymous threat actors broke in on March 28, 2026, and, as of April 12, have been extracting the files. EY did not say exactly what information was obtained or how many clients were affected. We also don’t know if this only applies to US customers or foreign customers as well. The attackers have since been removed from EY’s virtual facilities and the systems have been secured, the company confirmed.

So far, no hacking group has claimed responsibility for this attack, and the data has yet to appear anywhere on the dark web. EY clients should be on the lookout for unsolicited emails, especially those claiming to be from the professional services giant.

To help keep them safe, EY offers 24 months of free identity monitoring and restoration services through Experian.

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

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