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In a world where our lives are increasingly digital, data breaches have become the stuff of modern nightmares. One poorly secured server, one misconfigured setting, one clever hacker - and suddenly, millions (or even billions) of people are exposed. From tech giants to niche platforms holding surprisingly sensitive information, no one is truly immune.

Each of these breaches didn't just reveal the vulnerabilities of modern networks. They also underscored the growing importance of proactive cybersecurity and the very real consequences of getting it wrong.

In this updated 2025 list, we're counting down the biggest, most jaw-dropping data breaches in history. These weren't just IT headaches. They were global news, corporate disasters, and massive wake-up calls for businesses everywhere.

Let's dive in.

1. Yahoo!

Date: 2013-2016

Impact: Over 3 billion user accounts exposed

When it comes to data breaches, still holds the crown. What started as a 1-billion-account breach ballooned into a staggering 3 billion accounts compromised - basically, every single user on the platform.

Russian hackers infiltrated Yahoo's network over several years, using stolen credentials, forged cookies, and security vulnerabilities to collect personal data like:

• Names and email addresses

• Phone numbers and dates of birth

• Security questions and answers

• Account recovery information

Worse yet, Yahoo didn't disclose one of the key breaches from 2014 until years later, leading to 41 class-action lawsuits and a $35 million fine. This breach wasn't just large. It was legendary for all the wrong reasons.

2. Microsoft Exchange Server

Date: January 2021

Impact: Over 60,000 organizations affected globally

In early 2021, Microsoft's on-premise Exchange email servers were hit by a sophisticated cyberattack that exploited four separate zero-day vulnerabilities. A Chinese state-sponsored group called Hafnium used these flaws to:

• Access email accounts

• Install malware

• Exfiltrate sensitive information

• Move laterally through internal networks

Small businesses, local governments, and law firms were among the many affected. The attack was especially damaging because the targeted systems weren't cloud-based, meaning they didn't receive Microsoft's automatic patches.

Even after released security updates, many systems remained vulnerable due to late or failed patching. This breach highlighted just how risky outdated IT infrastructure can be.

3. Real Estate Wealth Network

Date: December 2023

Impact: 1.5 billion records exposed

This massive but lesser-known breach exposed over 1.16 TB of unsecured, unencrypted data from . The exposed database included:

• Contact details

• Mortgage and foreclosure information

• Tax IDs and bankruptcy records

• Property data for high-profile individuals

From Kylie Jenner to Nancy Pelosi, private ownership data was left wide open. With this information, cybercriminals could easily carry out social engineering attacks, identity theft, or financial fraud.

The breach raised major concerns about how much data private companies collect - and how little effort some take to protect it.

4. Facebook (Meta)

Date: April 2019

Impact: 533 million users affected

In 2019, discovered that personal data from over 500 million users had been scraped and leaked online. While it wasn't a traditional hack, the leak included:

• Names and locations

• Phone numbers

• Email addresses

• Birthdays

Facebook faced intense backlash for weak API security and a delayed response. The breach remained a lingering reminder that publicly available data can still pose serious risks when aggregated and dumped online.

5. Aadhaar (India)

Date: 2018

Impact: Over 1.1 billion people at risk

- the largest biometric ID program in the world - experienced a breach that could have compromised nearly every Indian citizen's identity. Investigations revealed that access to Aadhaar data was being sold for just a few dollars.

Leaked information included:

• Full names and addresses

• Biometric IDs

• Mobile phone numbers

• Government-issued identity numbers

The scale of the leak sparked a national debate on digital identity security and led to reforms in how Aadhaar data is handled and protected.

6. Equifax

Date: September 2017

Impact: 147 million Americans affected

, one of the three major credit reporting agencies, was breached in 2017 due to an unpatched software vulnerability. The result was catastrophic:

• Social Security numbers

• Credit card and driver's license information

• Birth dates and home addresses

The company's slow response and poor handling of the crisis made things worse. Equifax ultimately paid over $700 million in fines and settlements, and the breach remains one of the most damaging to consumer trust in recent memory.

7. LinkedIn

Date: June 2021

Impact: 700 million users

In this breach, data from nearly 93% of all users was scraped using the platform's own API. LinkedIn confirmed that the scraped data included:

• Full names and job titles

• Email addresses and phone numbers

• Profile links and account IDs

• Geolocation data

Though no passwords were leaked, the data was packaged and sold on the dark web. This incident proved that even public data, when collected in bulk, can lead to significant privacy risks.

What These Breaches Teach Us About Cybersecurity

Each of these breaches was a wake-up call. They show how fragile digital security can be and how devastating the consequences are when things go wrong.

Cyberattacks don't just cause technical headaches. They destroy trust, trigger lawsuits, attract fines, and damage reputations for years.

If your business handles sensitive customer data, your cybersecurity strategy needs to be proactive, not reactive. Protecting your infrastructure is no longer optional - it's mission critical.

Not sure where to start? At 海角社区, we help businesses stay ahead of cyber threats with managed IT services, real-time monitoring, and disaster recovery planning. Reach out today to secure your operations and reduce risk before you're the next headline.

Frequently Asked Questions About Data Breaches