Citigroup Data Breach History

This page tracks the Citigroup data breach history and cybersecurity incidents affecting Citigroup (United States). BreachHistory currently indexes 13 publicly disclosed or catalogued incidents spanning 2005 through 2013, with approximately 10.2 million records reported as exposed across all indexed events. These totals may include overlapping datasets or third-party estimates and should not be interpreted as unique affected users.

The Citigroup breach timeline includes major data breaches, cyber attacks, data leaks, credential exposures, API abuse, and other security incidents. Each incident provides details on the estimated records exposed, attack method, affected data types, and supporting public sources. Currently, 0 incidents are company-confirmed.

Largest Citigroup Data Breaches

The largest indexed incidents include the 2005 — Citigroup: Blame the messenger, 3.9M records, the 2005 — Citigroup: Customers are being notified that backup tapes…, and the 2010 — Citigroup: About 600,000 Citigroup customers got a shock…, along with additional historical incidents involving exposed passwords, public databases, and large-scale data scraping. Record counts originating from threat actors or leak sites should be treated as estimates unless confirmed by Citigroup or a regulator. Below is the list of large data breaches:

• 2005 2005 — Citigroup: Blame the messenger, 3.9M records — about 3.9M records exposed · Catalogued incident
• 2005 2005 — Citigroup: Customers are being notified that backup tapes… — about 3.9M records exposed · Catalogued incident
• 2010 2010 — Citigroup: About 600,000 Citigroup customers got a shock… — about 600.0K records exposed · Catalogued incident
• 2011 2011 — Citigroup: Data breach reported, 400K records — about 400.0K records exposed · Catalogued incident
• 2011 2011 — Citigroup: Hacking, 360,083 records — about 360.1K records exposed · Catalogued incident
• 2010 2010 — Citigroup: Less than 1% of Citbank card holders' names,… — about 360.1K records exposed · Catalogued incident
• 2011 2011 Online banking breach — 360k cardholders — about 360.0K records exposed · Catalogued incident
• 2013 2013 — Citigroup: Third big data breach from Citigroup, 150K records — about 150.0K records exposed · Catalogued incident

What Information Was Exposed?

Depending on the incident, exposed data may include email addresses, names, physical addresses, bank account details, health and medical (PHI) records, and other personal information (PII). The exact data varies between incidents, so review each breach page before assuming your information was affected.

Citigroup Data Breach 2026

At the time of this update, no Citigroup data breach has been catalogued for 2026. New incidents are added as official disclosures, regulatory filings, or credible cybersecurity reports become available.

What To Do If You Were Affected

If you believe your account may have been involved in a Citigroup data breach, change any reused passwords, enable multi-factor authentication (MFA), monitor your account for suspicious activity, and be cautious of phishing emails or fake breach notifications.

This Citigroup breach history is maintained by BreachHistory using public disclosures, regulatory filings, security research, and clearly labelled third-party claims. For the complete breach timeline, records exposed, incident details, and AI Breach Risk Score, explore the sections on this page.