← Back to blog
The Biggest Data Breaches in History: A Timeline of Digital Disasters
Cybersecurity
Feb 27, 2026
·
12 min read
16.7B+Records exposed since 2013
$4.88MAverage breach cost (2025)
277 daysAverage time to detect
Why Data Breaches Keep Getting Worse
Every year sets a new record. The attack surface expands as companies migrate to the cloud, adopt IoT devices, and accumulate decades of user data. Meanwhile, attackers are better funded, more organized, and increasingly leveraging AI. The result: breaches are bigger, costlier, and harder to detect than ever before.
The average organization takes 277 days to identify and contain a breach. That's 9 months of attackers silently exfiltrating data before anyone notices.
📅 Timeline of 15 Major Breaches
3 Billion accounts
Attack: State-sponsored hacking, forged cookies
💡 Yahoo didn't discover the breach for 3 years. The cover-up cost them $350M in their Verizon acquisition deal. Lesson: Invest in breach detection, not just prevention.
885 Million records
Attack: Authentication flaw (IDOR)
💡 Sensitive documents (bank statements, Social Security numbers) were accessible by simply changing the URL number. Lesson: Always implement proper access controls.
533 Million users
Attack: API scraping vulnerability
💡 Phone numbers and personal data of 533M users from 106 countries were scraped and leaked on a hacking forum for free. Lesson: Rate-limit and monitor API access.
500 Million guests
Attack: Persistent network intrusion
💡 Attackers were inside the Starwood reservation system for 4 years before Marriott acquired it — and nobody checked. Lesson: Security audits before M&A are critical.
700 Million profiles
Attack: API scraping
💡 Data of 93% of LinkedIn users was scraped and sold. LinkedIn argued it wasn't a "breach" since no private data was accessed. Lesson: Public data at scale becomes a privacy threat.
153 Million accounts
Attack: Network intrusion, poor encryption
💡 Passwords were encrypted with 3DES (not hashed), making them trivial to crack. Source code for Photoshop and Acrobat was also stolen. Lesson: Always hash passwords, never encrypt them.
147 Million people
Attack: Unpatched Apache Struts vulnerability
💡 Social Security numbers, birth dates, and addresses of half the US population were exposed because a known vulnerability wasn't patched for 2 months. Lesson: Patch management saves empires.
106 Million customers
Attack: Misconfigured WAF, SSRF
💡 A former AWS employee exploited a misconfigured firewall to access credit card applications stored on S3. Lesson: Cloud misconfigurations are the new open doors.
77 Million customers
Attack: Brute-force via unprotected router
💡 An unprotected router provided the initial entry point. T-Mobile has been breached 8+ times since 2018. Lesson: Repeated breaches signal systemic security culture failures.
18,000 organizations
Attack: Supply-chain compromise
💡 Russian state hackers inserted a backdoor into SolarWinds' Orion update, compromising US government agencies and Fortune 500 companies. Lesson: Your supply chain is your attack surface.
Ransomware — $4.4M paid
Attack: Compromised VPN password (no 2FA)
💡 A single leaked VPN password with no multi-factor authentication shut down fuel supply for the US East Coast. Lesson: Enable 2FA on every single remote access point.
25 Million users' vaults
Attack: Developer machine compromise
💡 Attackers compromised a developer's home computer, then used stolen credentials to access encrypted password vaults. Lesson: Even security companies aren't immune. Use strong master passwords.
6.9 Million users
Attack: Credential stuffing
💡 Reused passwords gave attackers access to accounts, which exposed genetic data of millions through the "DNA Relatives" feature. Lesson: Never reuse passwords — especially on sites with sensitive personal data.
2,700+ organizations
Attack: Zero-day SQL injection
💡 The Cl0p ransomware gang exploited a zero-day in Progress Software's MOVEit file transfer tool, affecting airlines, banks, and government agencies worldwide. Lesson: Minimize exposure of file transfer services.
2.9 Billion records
Attack: Unprotected database exposure
💡 Social Security numbers, names, and addresses of nearly every American were exposed by a background check company with virtually no security. Lesson: Data brokers are a massive, unregulated risk.
Attack Methods Breakdown
Which techniques led to the biggest breaches? Here's the pattern:
🔓 Credential Attacks
Credential stuffing, brute force, stolen passwords. Behind Colonial Pipeline, 23andMe, and many more. Fix: Unique passwords + 2FA.
🐛 Unpatched Vulnerabilities
Known CVEs left unpatched for weeks or months. Equifax and MOVEit are textbook examples. Fix: Automated patching and vulnerability scanning.
⚙️ Misconfigurations
Open databases, public S3 buckets, exposed APIs. First American and Capital One fell this way. Fix: Cloud security posture management.
🔗 Supply Chain
Compromising trusted software updates or third-party tools. SolarWinds and MOVEit exploited trust chains. Fix: Software bill of materials and vendor audits.
What Happens to Your Data After a Breach
Once your data is stolen, it follows a predictable path:
- Initial sale: The hacker sells the dataset on dark web markets within hours to days
- Credential stuffing: Automated bots try your email/password combo on hundreds of other sites
- Identity fraud: Full identity records (SSN, DOB, address) are used for loan applications and tax fraud
- Phishing campaigns: Your personal details make targeted phishing emails highly convincing
- Permanent circulation: Breached data never disappears — it's repackaged and resold for years
How to Protect Yourself
🔐 Use unique passwords — A password generator creates strong, random passwords for every account
🛡️ Enable 2FA everywhere — Read our complete 2FA guide
🔍 Monitor your exposure — Check haveibeenpwned.com regularly
❄️ Freeze your credit — Prevents fraudulent accounts being opened in your name
📧 Use email aliases — Give each service a unique email to limit blast radius
Frequently Asked Questions
What is the biggest data breach in history?
The Yahoo breach (2013-2014) affected all 3 billion accounts, making it the largest by user count. The 2024 National Public Data breach exposed 2.9 billion records including Social Security numbers.
How much does a data breach cost a company?
According to IBM's 2025 report, the average cost is $4.88 million. Healthcare breaches average $10.93 million — the highest of any industry for 14 consecutive years.
What should I do if my data is in a breach?
Change passwords immediately, enable 2FA, monitor financial statements for unauthorized activity, and consider freezing your credit with all three bureaus.
How do I check if my data has been breached?
Use Use Have I Been Pwned to check if your email appears in known breaches. Sign up for alerts to get notified of future breaches.
>Have I Been Pwned to check if your email appears in known breaches. Sign up for alerts to get notified of future breaches.
Are data breaches getting worse?
Yes. Both the frequency and scale continue increasing. 2023 saw a 72% increase in breaches over the previous record set in 2021, and 2024-2025 continued the trend.
Related Tools