HackingFinancial ServicesFinanceStolen CredentialsCustomer Data InvolvedGovernment IDIdentity (basic)MediumContained

MAINSTREET FEDERAL CREDIT UNION

bd_a7b719418247207b · schema v1 · pii pii-v1

Severity

Medium

Discovered

Jan 19, 2026

Filed

May 4, 2026

To disclose

—

Affected

2state residents only

Linked

4 filings

Confidence

66%

Full breach record for MAINSTREET FEDERAL CREDIT UNION →

Mainstreet Credit Union reported unauthorized access to a single employee Microsoft 365 email account between January 12 and 20, 2026. The breach affected two Nebraska residents, exposing personal information including Social Security numbers and driver's license numbers. Notifications were mailed on May 4, 2026, offering 12 months of credit monitoring via Kroll.

J jump to incidentP pin to compareR raw source

Incident timeline

undetected · 7 days

Jan 12, 2026

Begins

Jan 19, 2026

Discovered

May 4, 2026

Filed

This filing is one of 4 about the same incident.View merged incident

Linked disclosures

Why this link?

Regulatory filings (3) · sorted by filing gap

Indiana State AGbd_95a5aa203651f1602026-05-04Candidate
Massachusetts State AGbd_8d3fdafae2c42fb42026-06-18 · +45dVerified
New Hampshire State AGbd_dc1bebca2267480f2026-06-18 · +45dVerified

Name: MAINSTREET FEDERAL CREDIT UNION
norm: mainstreet federal credit union

Name: MAINSTREET FEDERAL CREDIT UNION
norm: mainstreet federal credit union
Industry: Financial Servicesllm

Discovered: Jan 19, 2026
Breach occurred: Jan 12, 2026 – Jan 20, 2026
Undetected for: 7 daysoccurrence → discovery
Materiality determined: —
Notification sent: May 4, 2026
Affected individuals: 2state-resident count only
Data types: Government IDIdentity (basic)
Data elements: Social Security number
Attack vector: Unauthorized Access
MITRE ATT&CK: T1078 Valid Accounts
Threat actor: External
Initial access: valid_credentials

During the incident: Instituted their incident response procedure and secured the account
Engaged Baker & Hostetler, LLP to provide legal advice
Engaged CRA to review forensic evidence
Reviewed all the emails and attachments that were stored in the account for any personal information
Began mailing notification letters to the two Nebraska residents via U.S. First-Class mail
Offering complimentary credit monitoring, fraud consultation and identity theft restoration services through Kroll
Changes made: Continue to assess its security procedures and training
Enhance the security of its email environment
Source: Quoted from the filing itself, not independently verified.

Compliance flags: — (clock not assessable for this source)

Status: No extraction artifact recorded for this disclosure.

Filing propagation · 4 filings · 4 states

View merged incident ↗

Indiana State AGMay 4 · first

Nebraska State AGMay 4 · first · this page

Massachusetts State AG+45d

New Hampshire State AG+45d

Pattern: first filing May 4 (IN), last Jun 18 (NH) — a 45-day rolling notification. Rolling spreads often mean counsel is filing as thresholds trip per state. Why this link?

Evidence ladder

Leak-site claim

Attacker assertion only. Establishes: claim date, group, alleged victim.

Press / market report

Unlocks: incident narrative, operational impact. Still no compliance clock.

State AG / regulator filingThis record

Unlocks: discovery date, data types, affected count, compliance clock.

SEC 8-K / victim statement

Unlocks: materiality, stated response, full audit trail. Ceiling removed.

Source URL: https://nebraska.gov/ago/data-breach/documents/f248ed4c-7ce3-4b48-b08b-922ebca5a81c.pdf
DisclosureLens links to the originating regulator URL — full filing bodies are not redistributed from public surfaces (§4.5).
Filed at: May 4, 2026
Raw hash: 55643254da9ee486e854840d4a6bc82a879228d3ea47d8987e2c317d9029ca9d

Linked disclosures

Regulatory filings (3) · sorted by filing gap

Reporting entityMAINSTREET FEDERAL CREDIT UNION

Victim entityMAINSTREET FEDERAL CREDIT UNION

Incidentdiscovered Jan 19, 2026

Stated responseInstituted their incident response procedure and secured the account

Complianceclock not assessable

Extraction provenanceno artifact recorded

Source provenancenebraska.gov