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MonitoringMontana AG filing · May 5, 2026

MemberSource Credit Union Reports Data Breach Affecting Members

MemberSource Credit Union in Montana reported a data breach impacting its digital network infrastructure on May 5, 2026. This incident exposed sensitive personal and financial data for an unspecified number of members. Affected individuals should take steps to protect against potential identity theft and financial fraud.

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, based in Montana, formally reported a data security incident on May 5, 2026. The breach involved its digital network infrastructure, though the specific nature of the cyberattack remains unspecified in public filings. This incident comes as financial institutions, which handle vast amounts of sensitive member data, continue to be significant targets for cybercriminals.

The exposed information includes a range of highly sensitive data categories. Affected members' Full Name, Social Security Number, Financial Account Number, Date of Birth, Routing Number, Credit Score Information, Transaction History, and Mailing Address were all potentially compromised. Such comprehensive data allows for various forms of fraud, including identity theft, unauthorized account access, and the opening of new lines of credit.

For those who received a data breach notification letter from MemberSource Credit Union, it is critical to act promptly. Review all financial account statements and credit reports for any suspicious or unauthorized activity. Consider placing a fraud alert or a credit freeze with the major credit bureaus (Equifax, Experian, and TransUnion) to prevent new accounts from being opened in your name.

Additionally, be wary of unsolicited communications, especially those asking for personal information, as scammers often use breach events to launch phishing attacks. While MemberSource Credit Union's investigation status is monitoring, individuals should remain vigilant and protect their personal and financial information.

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 breach filing: questions and answers

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.
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.
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.
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.
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.
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.
Do I need a MemberSource Credit Union data breach lawyer or attorney?
An attorney can read your notice and tell you whether a claim makes sense. A case review here is free, and data breach cases are usually handled on contingency, so there is no upfront cost.
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.

Source: Montana Attorney General filing

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