Hacks, thefts and disruption: The worst data breaches of 2025

TechCrunch looks back at the biggest data breaches, disruptive cyberattacks, and damaging hacks of 2025, from the raiding of U.S. government databases to a hack every month in South Korea.

Every year, TechCrunch looks back at the cybersecurity horror shows of the past 12 months — from the biggest data breaches to hacks resulting in weeks of disruption — to see what we can learn. This year, the data breaches were like nothing we’ve seen before.

Here’s our look back at some of the biggest security incidents of 2025, starting with:

The U.S. federal government was breached, several times over

The U.S. government remained one of the biggest targets in cyberspace. The year started with a brazen cyberattack by Chinese hackers on the U.S. Treasury, followed by the breaching of several federal agencies, including the agency tasked with safeguarding U.S. nuclear weapons, thanks to a SharePoint security flaw.

All the while, the Russian hackers were stealing sealed records from the U.S. Courts’ filing system, sending alarm bells ringing across the federal judiciary.

But nothing quite came as close as DOGE ripping through federal government departments and databases in what became the biggest raid of U.S. government data in its history.