The most recent alert from cybersecurity experts points to an old habit that millions of users still commit today: reusing the same password on different accounts. This behavior opens the door to one of today's most common and dangerous attacks, known as credential stuffing, a technique that doesn't require breaching complex systems and simply takes advantage of a lack of good digital habits.

What is credential stuffing really?

Credential stuffing (also called credential stuffing) involves cybercriminals using usernames and passwords stolen in leaks to test them on other platforms. If the person has the bad habit of repeating passwords, the attacker gains access without having to break any system.

The key to this attack is automation: with bots or scripts, attackers can test thousands of logins per minute on services like Netflix, Gmail, social networks, or banks. And the most dangerous thing is: the access obtained looks identical to that of a legitimate user, making it difficult to detect.

Examples abound. At PayPal (2022), more than 35,000 accounts were compromised in just two days. In the case of Snowflake, 165 organizations were affected because attackers used old passwords and took advantage of the lack of multi-factor authentication.

Why is repeating passwords so dangerous?

Reusing passwords is like using a single key to open your house, your car, your office, and even the safe. If someone gets hold of it, everything is compromised.

The problem is that data breaches are becoming more frequent and massive. In 2025, for example, 16 billion records containing user credentials were exposed in misconfigured repositories. Just a month earlier, 184 million accounts from services like Google, Apple, Facebook, banks, and even government portals had been found leaked.

Each of these leaks is new fertile ground for attackers. Repeating passwords increases their risk: if one service is compromised, all of their other accounts become vulnerable. Worse still, many victims don't even know their credentials have been stolen until someone gains unauthorized access to their information.

What's the best way to protect yourself?

The first golden rule is simple: don't repeat passwords. Each service should have a unique, long, and complex key. Since this is almost impossible to remember manually, it's best to rely on a password manager, which allows you to store encrypted credentials and automatically generate secure keys.

The second step is to activate two-factor authentication (2FA). With this system, even if a cybercriminal obtains your password, they'll need a second code to enter. That second step is often the difference between a failed attack attempt and a stolen account.

Furthermore, it's advisable to periodically check whether your passwords have been leaked in a data breach and change them immediately if they appear compromised. There are specialized sites that allow you to easily check this.

Credential stuffing isn't a sophisticated attack, but it is highly effective because it relies on human error. The defense is clear: use unique passwords, always activate a second authentication factor, and maintain digital discipline. Ultimately, protecting your online identity is more a matter of habit than advanced technical knowledge.