List of data breaches and cyber attacks in May 2021 – 116 million records breached

For the second month in a row, ransomware has dominated our list of data breaches and cyber attacks. Of the 128 publicly disclosed incidents that we discovered in May, more than 40% of them were ransomware attacks.

But, of course, the nature of ransomware attacks makes it hard for organisations to determine how many records were affected. That partially explains why May’s total of 115,861,330 breached records is comparatively low.

By contrast, we disclosed 1 billion breached records in April, and almost 4 billion in the first four months of the year.

As always, you can find the full list of incidents below, with those affecting UK organisations listed in bold.


Cyber attacks


Data breaches