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MonitoringMontana AG filing · May 5, 2026

MemberSource Credit Union Data Breach Exposes Member Financial Details

MemberSource Credit Union reported a data breach in Montana on May 5, 2026, which may have exposed sensitive financial and personal information belonging to its members. Individuals who received a breach notification letter should understand the implications of this incident and evaluate their next steps.

This breach is real, not a scam. MemberSource Credit Union officially reported it to the Montana Attorney General on May 5, 2026.

Reviewed by David S. Harris, Esq., data breach and class action attorney (Florida Bar No. 0112739). Free consultation: 786-306-7278

Received a MemberSource Credit Union notification letter? Find out in minutes if you qualify for compensation.

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State
Montana
Breach date
June 3, 2025
Reported
May 5, 2026

What may have been exposed

  • Full Name
  • Social Security Number
  • Financial Account Number
  • Date of Birth
  • Routing Number
  • Credit Score Information
  • Transaction History
  • Mailing Address

MemberSource Credit Union, a financial cooperative providing banking services in Montana, formally reported a data security incident on May 5, 2026. This breach occurred on June 3, 2025, and involves the compromise of its digital network infrastructure. This filing serves as official notice to affected account holders that their private information may have been accessed by unauthorized parties.

The exposed information in this breach includes a range of sensitive personal and financial identifiers. Specifically, the data types reported as potentially compromised are: Full Name, Social Security Number, Financial Account Number, Date of Birth, Routing Number, Credit Score Information, Transaction History, and Mailing Address.

Such a comprehensive exposure of personal and financial data carries significant risks for affected individuals. The combination of Full Name, Social Security Number, and Date of Birth can be used for sophisticated identity theft, potentially leading to fraudulent credit applications, unauthorized loans, or tax fraud. Additionally, the compromise of Financial Account Numbers, Routing Numbers, and Transaction Histories directly threatens members' liquid assets, opening pathways for unauthorized transfers, fraudulent debits, and account takeover schemes.

As a financial institution, MemberSource Credit Union is entrusted with highly sensitive data and is subject to stringent regulations designed to protect nonpublic personal information. These regulations require robust security measures, regular audits, and prompt patching of vulnerabilities. The occurrence of a data breach raises questions about the adequacy of the protective measures in place prior to the incident.

For those who have received an official data breach notification letter from MemberSource Credit Union, this document is a critical record confirming the exposure of your private data. Understanding the specific details outlined in your letter is essential for assessing your individual risk. Learning more about this incident and its potential impact can help you navigate the situation and explore any available options.

If you received a notification, we invite you to connect for a free, no-obligation case review. Our team can help you understand the legal landscape surrounding this breach and discuss what your notification letter means for your specific situation. This review is an opportunity to get clarity on your standing without any out-of-pocket cost.

What to do if you were affected

Based on the categories of information reported in this filing, these steps can help limit the risk of identity theft and fraud.

  • Freeze your credit

    Place a free credit freeze with Equifax, Experian, and TransUnion. A freeze blocks new accounts from being opened in your name and can be lifted anytime.

  • Watch your financial accounts

    Review bank and card statements for unfamiliar activity and turn on transaction alerts. Report anything you don't recognize to your bank right away.

  • Stay alert to targeted scams

    Be cautious of calls, texts, or emails that reference this breach. Legitimate organizations won't ask you to confirm sensitive details through an unsolicited message.

  • Keep your notification letter

    Save the notice you received. It documents that your information was involved and is often needed to enroll in any credit monitoring offered or to join a related legal claim.

MemberSource Credit Union data breach notice and letter questions

Is the MemberSource Credit Union data breach letter legit or a scam?
A notice from MemberSource Credit Union in the mail matches the breach MemberSource Credit Union reported to the Montana Attorney General on May 5, 2026. Check that the company name and dates in your letter match that filing. A real notice of data security incident won't ask for your password, Social Security number or a payment — if it does, contact MemberSource Credit Union through a phone number or website you find yourself.
Where can I see the official MemberSource Credit Union breach notice?
MemberSource Credit Union's report is published by the Montana Attorney General: https://dojmt.gov/office-of-consumer-protection/reported-data-breaches/#mt-membersource-credit-union-2026 Compare it with the letter you received to confirm the dates and details match.
How many people were affected by the MemberSource Credit Union data breach, and what was exposed?
The filing does not give a count of affected people and lists the following information as involved: Full Name, Social Security Number, Financial Account Number, Date of Birth, Routing Number, Credit Score Information, Transaction History, Mailing Address. Your own letter is the best guide to what was exposed about you, since notices are usually tailored to each person.
Did MemberSource Credit Union offer free credit monitoring?
Any free monitoring MemberSource Credit Union is offering will be described in the notice you received, along with an activation code and a sign-up deadline. Because Social Security numbers are listed in this filing, identity monitoring and a credit freeze matter more than usual. Enrolling does not give up your right to bring a claim.
What should I do after getting the MemberSource Credit Union data breach notice?
Keep the letter and the envelope, and note the date it arrived. Freeze your credit with Equifax, Experian and TransUnion, change any passwords the notice mentions, and sign up for any free credit monitoring the letter offers. Then check whether you may have a claim.
Is there a MemberSource Credit Union data breach class action lawsuit?
Law firms often open an investigation after a breach notice like this one, and a class action lawsuit may follow. This page doesn't confirm that a lawsuit has been filed against MemberSource Credit Union. You usually don't have to join a class action to be included — if a settlement is reached, class members are notified and can file a claim.
Do I need a MemberSource Credit Union data breach lawyer or attorney?
Talking to a data breach attorney costs nothing here. A lawyer can read your notice, explain your rights under your state's law and tell you whether a claim makes sense.
How much could a MemberSource Credit Union data breach settlement or claim be worth?
There is no set amount, and no MemberSource Credit Union settlement is confirmed here. In past data breach settlements, payments depended on what data was exposed and on documented losses — fraud, out-of-pocket costs and time spent dealing with the breach. The filing lists Full Name, Social Security Number, Financial Account Number as involved. Keep receipts and records; they're what damages claims are built on.
Can I sue MemberSource Credit Union over the data breach?
It depends on what was exposed, the law in Montana and your own state, and whether you've been harmed. Most people take part through a class action rather than suing alone. Keep your notification letter — it's the proof that connects you to the breach.

Source: Montana Attorney General filing

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