183 Million Passwords Just Leaked—Is Yours One of Them?

The Biggest Password Leak You Have Never Heard Of

In October 2025, Have I Been Pwned added 183 million email and password combinations to its database. The data did not come from a single company breach. It came from millions of infected computers around the world.

The dataset, called the Synthient Stealer Log Threat Data, contains 3.5 terabytes of stolen credentials. Security researchers found 23 billion rows of data, including 16.4 million email addresses that had never appeared in any previous breach.

At peak activity, the criminals behind this operation were harvesting 600 million stolen credentials per day.

How Infostealer Malware Works

Infostealer malware is not like traditional viruses that announce themselves with pop ups or ransomware demands. It operates silently, recording everything you type without any visible sign of infection.

When you log into any website on an infected computer, the malware captures three pieces of information: the website address, your email or username, and your password. This happens in real time as you type.

But passwords are just the beginning. Modern infostealers like Lumma, RedLine, and StealC also grab:

• Session cookies that let attackers bypass two factor authentication
• Saved credit card numbers from your browser
• Cryptocurrency wallet keys and seed phrases
• Discord tokens and VPN credentials
• Browser autofill data including addresses and phone numbers

The Numbers Are Staggering

The scale of infostealer infections in 2025 is unprecedented:

• 3.9 billion passwords were leaked from 4.3 million infected devices
• Infostealer attacks increased 58% year over year
• 64% of mid to large enterprises had at least one infection in the past five years
• 54% of ransomware victims had their credentials appear in stealer logs before the attack
• Lumma, StealC, and RedLine account for over 75% of all infections

According to the 2025 Verizon Data Breach Investigations Report, 32% of all breaches globally involved stolen credentials. Nearly half of those credentials came from infostealer malware.

How the Data Was Collected

Benjamin Brundage, a college student working with Seattle based cybersecurity firm Synthient LLC, spent nearly a year infiltrating the criminal ecosystem where stolen credentials are traded.

His team built monitoring systems that tracked Telegram channels where hackers buy and sell stolen data. At peak activity, these channels processed 600 million credentials in a single day.

The breach technically occurred in April 2025, but it took until October for the data to be verified and added to Have I Been Pwned. That means stolen credentials circulated in criminal forums for six months before the public knew they were compromised.

Why This Makes Your Inbox a Target

Stolen credentials do more than give attackers access to your accounts. They reveal your entire digital footprint.

When attackers have your email paired with the websites where you use it, they can craft highly targeted phishing campaigns. They know you have a Netflix account, an Amazon account, a bank login. They know exactly which fake emails will seem legitimate to you.

Email tracking compounds this threat. When attackers send phishing emails, embedded tracking pixels confirm whether your address is active and whether you engage with suspicious messages. This reconnaissance helps them identify which victims are worth pursuing.

Gblock protects against this by blocking the spy pixels and click tracking that attackers use to validate their target lists. When you do not trigger their tracking, you become invisible to their follow up campaigns.

How to Check If You Are Affected

Visit Have I Been Pwned and search for your email address. The Synthient Stealer Log data is now searchable alongside other breaches.

If your email appears in this breach, assume your password for that service is compromised. But here is the uncomfortable truth: even if your email is not in this specific dataset, infostealer infections are so widespread that your credentials may appear in the next one.

What to Do Right Now

If you find your email in the breach, or want to protect yourself proactively:

• Change passwords immediately for any accounts using the exposed credentials
• Enable two factor authentication everywhere, preferably using an authenticator app rather than SMS
• Use a password manager to generate unique passwords for every site
• Run a full antivirus scan to check for active infostealer infections
• Review your browser for suspicious extensions that may be harvesting data
• Consider using Gblock to block the tracking pixels that help attackers verify active email addresses

The Uncomfortable Reality

Infostealer malware has become the fastest growing malware category, overtaking ransomware in terms of deployment. The criminals behind these operations have industrialized credential theft at a scale that was unimaginable just a few years ago.

Your password is no longer just a secret between you and a website. It is a commodity being traded in bulk on criminal marketplaces. The best defense is assuming your credentials are already compromised and building your security around that reality.

Use unique passwords. Enable two factor authentication. And protect your inbox from the tracking that helps attackers find their next victim.

Your email is ground zero for most attacks. Gblock helps you stay invisible to the tracking that makes you a target.