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Data breaches → China Software Developer Network

Was your data in the China Software Developer Network breach?

2011 · csdn.net · ~6,414,990 accounts exposedCritical severity · 10/10

China Software Developer Network (csdn.net) suffered a data breach in 2011 that exposed around 6,414,990 accounts. If you had an account, some of your personal data may be circulating in leaked databases. The fastest way to know is to check your own email — free, in about 30 seconds, no password required.

What happened

In 2011, the China Software Developer Network (CSDN) suffered a data breach that exposed over 6M user records. The data included email addresses alongside usernames and plain text passwords.

Breach details sourced from Have I Been Pwned, the industry-standard breach database. Risk analysis by Nullivo.

What was exposed, and why it matters

Not all breaches carry the same risk — what matters is which fields leaked. Here is what the China Software Developer Network breach exposed and what each item actually enables:

Passwords

Attackers replay leaked passwords across other sites (“credential stuffing”). Because most people reuse passwords, one leak often unlocks email, shopping and banking accounts elsewhere.

Names and usernames

Links this leak to your other accounts — a reused username lets anyone build a profile of you across platforms.

Email addresses

Puts you on spam and phishing lists, and confirms to attackers that you hold an account with this service — which makes impersonation emails more believable.

What to do if you were affected

These steps are ordered for this specific breach — the most urgent action given what leaked comes first.

  1. Passwords: Change this password everywhere you have reused it, starting with your email account — whoever controls your email can reset everything else.
  2. Names and usernames: Search your usual username to see what else it exposes, and use distinct handles for sensitive accounts.
  3. Email addresses: Treat any message referencing this service with suspicion, and never act on links in unexpected emails.
  4. Check whether your own email appears in this breach — run a free scan to confirm before you spend time on the steps above.

How urgent is this now?

This breach is over 15 years old. Old credentials still cause harm — leaked passwords from a decade ago are still tried against new accounts every day.

Passwords are the reason breach age matters less than people expect. Leaked credentials are compiled into wordlists that get tried against new services for years afterwards, so a password exposed here is unsafe to use anywhere, ever again.

Remember: a breach can't be "un-leaked" — once a database is out, it exists in countless copies. The goal is to make the leaked data useless: change what can be changed, lock down what can't, and remove what has been republished.

Check if your email was exposed.Nullivo's free scan checks your own verified email against known breaches — including China Software Developer Network — in 30 seconds. No password, no signup, and we only ever scan your own email. Run your free scan →

Frequently asked questions

What data was exposed in the China Software Developer Network breach?

The China Software Developer Network breach exposed passwords, names and usernames, email addresses. Attackers replay leaked passwords across other sites (“credential stuffing”). Because most people reuse passwords, one leak often unlocks email, shopping and banking accounts elsewhere.

How many people were affected by the China Software Developer Network breach?

Around 6,414,990 accounts were exposed, making it a large breach.

What should I do if I had a China Software Developer Network account?

Change this password everywhere you have reused it, starting with your email account — whoever controls your email can reset everything else. You can check whether your own email appears in this breach with a free Nullivo scan — no password required.

Breaches that exposed similar data

If the China Software Developer Network breach affected you, these breaches exposed comparable information — worth checking too, since leaked datasets are routinely combined.

See all breaches we cover →