Jefferson County Data Breach History
WebsiteJefferson County government provides local services; multiple US states have Jefferson Counties.
This page shows all data breaches of Jefferson County. View the complete breach timeline, records exposed, root causes, and AI breach risk score. BreachHistory tracks disclosed data breaches worldwide.
Data Breach Timeline — All Jefferson County Breaches
- 2015 2015 — Jefferson County: Jefferson County residents were alerted to a… Unknown records Share
- 2011 2011 — Jefferson County: Around 6,500 ACT Explore test results for 8th… 6.5K records Share
- 2008 2008 — Jefferson County: A special education technician had a personal… 2.9K records Share
- 2008 2008 — Jefferson County: Jefferson County Clerk Jennifer Maghan said she… 1.6M records Share
Jefferson County Data Breach Summary
This page tracks the Jefferson County data breach history and cybersecurity incidents affecting Jefferson County. BreachHistory currently indexes 4 publicly disclosed or catalogued incidents spanning 2008 through 2015, with approximately 1.6 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 Jefferson County 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 Jefferson County Data Breaches
The largest indexed incidents include the 2008 — Jefferson County: Jefferson County Clerk Jennifer Maghan said she…, the 2011 — Jefferson County: Around 6,500 ACT Explore test results for 8th…, and the 2008 — Jefferson County: A special education technician had a personal…. Record counts originating from threat actors or leak sites should be treated as estimates unless confirmed by Jefferson County or a regulator. Below is the list of large data breaches:
- 2008 2008 — Jefferson County: Jefferson County Clerk Jennifer Maghan said she… — about 1.6M records exposed · Catalogued incident
- 2011 2011 — Jefferson County: Around 6,500 ACT Explore test results for 8th… — about 6.5K records exposed · Catalogued incident
- 2008 2008 — Jefferson County: A special education technician had a personal… — about 2.9K records exposed · Catalogued incident
What Information Was Exposed?
Depending on the incident, exposed data may include email addresses, passwords, phone numbers, names, profile information, account identifiers, and other personal information (PII). The exact data varies between incidents, so review each breach page before assuming your information was affected.
Jefferson County Data Breach 2026
At the time of this update, no Jefferson County 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 Jefferson County 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 Jefferson County 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.