Reusing passwords may feel like a harmless shortcut – until a single breach opens the door to multiple accounts.

Reusing the same password across different accounts might seem convenient, but it creates a single weak spot that can put your whole digital life at risk. This habit makes you an easy target for credential stuffing — a method where attackers take stolen username‑and‑password pairs and try them on many other websites. If you use the same login details everywhere, one leaked password can unlock several unrelated accounts.

Credential stuffing is like someone finding a skeleton key that opens your house, your office, and your safe all at once. And getting that “key” isn’t hard. Attackers can collect exposed credentials from old data breaches, buy them on criminal marketplaces, or use infostealer malware to grab passwords directly from infected devices and web browsers.

Why credential stuffing works so well

The main reason this attack is so effective is simple: many people reuse passwords across important accounts like banking, email, social media, and shopping sites.

Once attackers get hold of a username and password, they can try the same combination on countless other services. Automated bots make this easy. They can test huge numbers of stolen credentials, switch IP addresses, and behave like real users to avoid detection.

Credential stuffing is also different from brute‑force attacks. Brute force relies on guessing passwords, which triggers lots of failed logins and alerts. Credential stuffing uses valid passwords that were leaked in the past, so the attack often goes unnoticed.

The threat has grown even worse recently. Infostealing malware has become widespread, quietly collecting passwords from browsers and even putting password managers at risk. Attackers also use AI‑powered scripts that mimic human behaviour, helping them slip past basic bot protections and test stolen credentials at massive scale.

Real‑world examples

• PayPal (2022): Nearly 35,000 customer accounts were accessed through credential stuffing. PayPal itself wasn’t breached — attackers simply used old leaked passwords that users had reused elsewhere.
• Snowflake attack wave (2024): Around 165 organisations were affected. Attackers used credentials stolen by infostealer malware to access multiple Snowflake accounts, and some victims later faced ransom demands.

How to protect yourself

• Never reuse passwords. Use a password manager to generate and store strong, unique passwords for every account.
• Enable two‑factor authentication (2FA). Even if someone knows your password, it is very hard to log in without the second step.
• Check whether your details have been exposed. Services like haveibeenpwned.com can alert you if your email or passwords have appeared in past breaches. If they have, change your passwords immediately — especially for sensitive accounts.

Conclusion

Credential stuffing is cheap, simple, and highly scalable. It works because it takes advantage of common password habits and outdated security assumptions. Strong, unique passwords and basic security hygiene are essential. These aren’t optional anymore — they’re the minimum needed to stay safe online.