What was exposed, when it happened, and which databases confirm it.
- accounts
- 6,428,632
- Breached
- December 21, 2011
- Last Update
- November 27, 2025
Were you caught in this breach?
Search your email, phone number or username against every record CheckLeaked indexes.
Your address never leaves this page: it is hashed in your browser and only a short fragment of that hash is sent.
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.
Compromised Info
- Email addresses
- Passwords
- Usernames
Attestation
Four independent databases catalog this breach and they do not always agree. Each lane below is one source’s own count.
Sources & Link Methods
- HIBP
FAQ
What was leaked in the CSDN breach?
The CSDN breach exposed: Email addresses, Passwords, and Usernames.
When did the CSDN breach happen?
The CSDN breach was disclosed on December 21, 2011 and affected 6,428,632 records.
Am I affected by the CSDN breach?
Search your email, phone or username at checkleaked.cc to find out whether your data appears in the CSDN leak.