Your personal data might have been broadcast to hundreds of advertisers without consent. Register for updates if this claim is taken forward by one of our partner UK law firms.
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Overview
The Irish Council for Civil Liberties (ICCL) is taking on Microsoft, accusing the tech giant of breaking GDPR rules. The issue? A behind-the-scenes process called real-time bidding, where your personal information is shared with advertisers the moment you visit a website.
The ICCL says Microsoft is collecting and sharing more data than it should – and not always with proper consent.
We are monitoring the situation closely. Register your interest and we’ll keep you updated if one of our regulated UK partner law firms is able to take this claim forward.
Microsoft data breach – At a glance
What do we know about the alleged Microsoft data breach?
“People’s intimate secrets such as their relationship, work and financial status are broadcast by Microsoft into the Real-Time Bidding advertising system. That system is a black hole of data open to any malicious actor and represents a huge data breach of millions of people’s information”.
How Join the Claim works
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If a partner law firm takes this claim forward, we’ll let you know the next steps and how to join.
Latest updates on the alleged Microsoft data breach
June 2026
The Irish Commercial Court held a pivotal preliminary hearing to resolve a fundamental pre-trial dispute.
July 2025
Join the Claim opens registration to those interested in finding out more about any future claim.
News of the data breach is reported in the media.
June 2025
A High Court Judge grants the ICCL permission to advance the lawsuit on behalf of consumers on an "opt-out" basis
May 2025
The ICCL applies to High Court to begin proceedings against Microsoft. Proceedings are then formally launched in Ireland.
May 2018
GDPR comes into force.
We’ll provide more updates on the Microsoft data breach as they occur.
Who could be affected by the alleged Microsoft data privacy breach?
If you ever used Microsoft, your data might have been shared without your consent. Register for updates if a partner UK law firm takes this claim forward.
Frequently asked questions
This claim is about how Microsoft’s online advertising system handles your personal data. The ICCL alleges that Microsoft is breaching GDPR rules by sharing sensitive information, like your location, interests, or even political views, with hundreds of advertisers without your clear consent. They argue this happens through a process called real-time bidding, and that it’s putting users’ privacy at risk.
It’s a system where ads are bought in milliseconds based on your real-time data—like browsing history or location—with no clear path of consent or control over what happens after it’s shared.
Microsoft’s RTB system covers users of Windows, Xbox, Edge, web‑based Office, and apps using Xandr data. If UK-based users have been caught in this system, a successful Irish case could pave the way for UK cases.
We’re keeping a close eye on this. If a UK version is filed, we’ll notify you immediately, help you check eligibility, and put you in touch with a trusted law firm.
No. Registering simply means you’ll receive updates. If a law firm later takes on the case, you’ll be given the option to learn more about the process and any potential costs before deciding whether to take part.
A group action claim allows people affected by the same issue to take action together. This strength in numbers helps stand up to big organisations. Join the Claim helps connect people with law firms so these actions have real impact.
We are not a law firm. Our role is to keep people informed about potential group actions if one of our regulated UK partner law firms is able to take this claim forward.
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When you register your interest with Join the Claim, we’ll keep you updated if one of our regulated partner law firms decides to take the claim forward. However, other law firms may also investigate or pursue claims independently of Join the Claim.
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