China Software Developer Network 2011 Data Breach
ObscureIQ Breach Intelligence
Low SeverityWebsite / service breach
China Software Developer Network (CSDN) Breach (2011): 6.4 Million User Accounts Including Plaintext Passwords Exposed
Chinese developer community and technology content platform.
Verified by ObscureIQ Intelligence
34/100Breach Risk Index
6Data Value
40Market Recency
223dSince Breach
Breach Intelligence Summary
Entity: China Software Developer Network · Actor: Unknown · Sources: 3 references
Attack: Unknown
Profile: Platform · Developer content and resources · Technical community platform · China
Timeline: Breach (2011-12-21) · Indexed (Nov 27, 2025) · Year (2011)
Exposure: 6.4M records · 3 fields: Email Address, Password, Username
Status: Confirmed
Executive Summary
On 21 December 2011, the CSDN user database was publicly leaked, exposing about 6.4 million accounts with email addresses, usernames, and plaintext passwords. CSDN stated the leaked data dated to around September 2010, from a period before it stopped storing passwords in clear text. The incident helped trigger a wider wave of Chinese site breach disclosures that month.
ObscureIQ assessment: High risk of credential reuse and account takeover. Developer communities are valuable targets for malware distribution and targeted phishing.
Breach Impact
Plaintext developer credentials are immediately usable and, given the technical user base, elevate risk of downstream compromise of code repositories and other systems through password reuse.
About China Software Developer Network
CSDN (China Software Developer Network) is one of China’s largest online communities for software developers, offering forums, blogs, and technical resources.
Why They Hold Your Data
Developer platforms collect user accounts, emails, usernames, passwords, and technical activity tied to coding resources, forums, and software sharing.
Recent Developments
Chinese authorities arrested individuals in connection with the incident, and CSDN moved away from clear-text password storage after the exposure.
Data Points Exposed
3 verified field types
Email Address
Password Critical
Username
Field names are shown in full for clarity and search visibility. Canonical machine keys are emitted only in this page’s structured data.
Exploitation & Downstream Threats
Threat Activity:High
Primary downstream threats:
- Credential stuffing against reused passwords across other platforms
- Targeted phishing campaigns using exposed email addresses
Threat vectors:
- Phishing, credential stuffing & account takeover
- Credential stuffing & account takeover
- Cross-platform tracking & credential stuffing
Recommended Actions
If you believe your information may be included:
Change Reused Passwords
Update this account and anywhere you reused the password; use a manager.
Enable MFA Everywhere
Turn on multi-factor authentication on email first, then financial accounts.
Report & Recover
If you spot misuse, start an official recovery plan and report fraud.
Frequently Asked Questions
What happened in the China Software Developer Network breach?▾
On 21 December 2011, the CSDN user database was publicly leaked, exposing about 6.4 million accounts with email addresses, usernames, and plaintext passwords. CSDN stated the leaked data dated to around September 2010, from a period before it stopped storing passwords in clear text. The incident…
What data was exposed?▾
Verified fields include Email Address, Password, Username.
What should I do if I was affected?▾
Change reused passwords, enable MFA, and (if identity or financial data is involved) freeze your credit and monitor your accounts.
Sources & References
Every claim on this page is traceable. This breach draws on:
Breach Index
Breach Index
DataBreach.com
ObscureIQ Intelligence
ObscureIQ proprietary analysis
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