Wisner Baum data breach: a one-day network intrusion at the law firm, and files that may have left

Date	Event
October 8, 2025	Unauthorized access to the firm's network begins
October 9, 2025	Wisner Baum detects unusual activity, secures its systems and brings in outside experts
January 21, 2026	Letters
January 23, 2026	Reports to Massachusetts (258 residents) and Vermont

What happened at Wisner Baum?

The firm caught the intrusion within about a day. Its letter says it first became aware of the incident on October 9, 2025, when it detected unusual activity on its network, and that it secured its systems and engaged independent cybersecurity professionals. The investigation dated the start to October 8. The letter does not name the attacker, say how the network was entered, or mention ransomware.

One line stands out. The firm says it has taken all possible steps to help ensure that the data that may have been taken has been deleted. The letter does not say how deletion was sought or confirmed. The double extortion guide covers how notices describe stolen data and demands.

Why would a law firm have my medical and bank information?

The letter does not say whose files these were or why the firm held them. It lists the data that may have been in them: names, driver's license numbers, bank account and routing numbers, and medical information. The law firm breach notice guide compares other firms' letters. The guide to letters from a company you never dealt with explains how firms come to hold other people's documents.

What information was exposed?

Record	People	Data it marks
Wisner Baum letter, Vermont copy (January 21, 2026)	Not given	Name, driver's license number, bank account and routing numbers, medical information
Massachusetts OCABR, report 2026-113 (January 23, 2026)	258	SSNs, driver's licenses

The two records differ. The letter does not list Social Security numbers, while the Massachusetts record marks them. The letter lists bank account numbers and medical information, which the Massachusetts record does not mark. Letters to different people can carry different data lists, so both are kept as filed.

What is Wisner Baum offering?

Twelve months of single-bureau credit monitoring, a credit report and a credit score through Cyberscout, a TransUnion company, with fraud assistance. Enrollment had to happen within 90 days of the letter, so for a letter dated January 21, 2026 the window closed in April 2026. The firm says it has added stronger protections and more monitoring. The credit monitoring guide compares offers.

What the documents leave open

• How the outsider got into the network.
• Who took the data and what contact, if any, the firm had with them.
• The total number of people notified across all states.