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MonitoringMontana AG filing · May 5, 2026

MemberSource Credit Union Data Breach: Understanding Your Notification Letter

MemberSource Credit Union reported a data breach to the Montana Attorney General in May 2026, compromising sensitive personal and financial information. If you received an official notification letter, it confirms that your data has been exposed, necessitating a review of your legal rights. This incident raises questions about the credit union's security practices and its duty to protect member information.

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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

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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 formally reported a data security incident to the Montana Attorney General on May 5, 2026. This breach involved the compromise of the credit union's digital network infrastructure, an event that occurred on or about June 3, 2025. If you have received a letter regarding this incident, it means your private information was among the records accessed by unauthorized parties.

The exposed data categories include Full Name, Social Security Number, Financial Account Number, Date of Birth, Routing Number, Credit Score Information, Transaction History, and Mailing Address. The compromise of such detailed personal and financial information creates significant risks. For instance, your Full Name, Date of Birth, and Social Security Number are prime targets for identity theft, potentially leading to fraudulent accounts or loans. Furthermore, the exposure of your Financial Account Number, Routing Number, and Transaction History could enable unauthorized financial transactions or account takeover attempts.

Financial institutions like MemberSource Credit Union are legally bound by stringent regulations, such as the Gramm-Leach-Bliley Act and various state data protection laws, to safeguard your nonpublic personal information. These laws mandate that credit unions maintain robust security measures, including encryption, regular audits, and timely vulnerability patching. The occurrence of a data breach, particularly one involving such sensitive data, suggests that these critical security obligations may not have been fully met prior to the incident.

For those who have received an official data breach notification letter from MemberSource Credit Union, this correspondence is more than just an alert; it serves as a legal confirmation that your personal data has been compromised due to what may be corporate negligence. This notice establishes the concrete injury necessary to explore your legal rights and potential avenues for accountability.

Understanding the specifics of your notification letter and how it relates to the credit union's broader obligations is crucial. Our firm provides free case reviews to help affected individuals understand the legal implications of this breach and whether participation in a class action lawsuit could be an appropriate next step for holding the institution accountable for its security lapses. There are no out-of-pocket costs to you, as our firm operates on a contingency fee basis.

Received the MemberSource Credit Union notification letter? The MemberSource Credit Union case file tracks this filing.

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.

Your legal options after the MemberSource Credit Union data breach

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.
Do I need a MemberSource Credit Union data breach lawyer or attorney?
A data breach attorney can explain whether the law in your state gives you a claim and what proof you'd need. Reviews here are free, and these cases are normally taken on contingency.
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.
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.
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 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.
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.
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.
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.

Source: Montana Attorney General filing

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