Seyfarth Shaw data breach: client documents emailed to an outsider, 56,755 people

What happened at Seyfarth Shaw?

On August 18, 2026 the firm found that a limited number of documents containing personal information had been acquired by someone who should not have them. It says it checked the security of its network and opened an investigation. That investigation, the letter says, found no evidence of unauthorized access to the network; the event was limited to documents sent by email to an unauthorized recipient.

Reuters reported that the firm described the cause as a social engineering attack: someone posing as the firm's IT help desk persuaded a staff member to email client documents to an outside account. The firm told Reuters the incident was isolated to a single employee and that its controls kept the attacker out of its systems.

Date	What happened	Source
August 18, 2026	Documents with personal information acquired; firm opens an investigation	Seyfarth notice; Indiana report
September 18, 2026	Date on the letters; notice filed in California	Seyfarth notice; Indiana report
By September 23, 2026	Notice filed with the Texas attorney general	Reuters
90 days from the letter	Last day to enroll in the credit monitoring	Seyfarth notice

The letters went out 31 days after the documents were taken. The notice-delay guide shows how that compares with other 2026 notices.

Why did Seyfarth Shaw have my information?

The letter says the firm obtained it in the course of legal services it performed. Reuters describes the firm as best known for real estate and management-side labor and employment work. The notice does not name the clients or say how each recipient is connected to them. If you have never heard of the firm, the guide to why you got a breach letter from a company you never dealt with explains how this happens.

What information was exposed?

Name and Social Security number. The filed letter lists nothing else: no dates of birth, account numbers or health data.

How many people were affected?

56,755 in total, per Indiana's report, including 149 Indiana residents. Reuters, writing on September 23, 2026, had only the Texas and California filings. The firm's own letter gives no count. The largest data breaches of 2026 shows where it sits this year.

Texas's attorney general lists a report from Seyfarth Shaw LLP, posted on September 21, 2026, with 305 Texans affected. The Texas record lists names and Social Security numbers among the information involved. The Texas ranking lists 2026's largest reports. The figure counts Texans only.

What is Seyfarth offering, and how do I enroll?

Single-bureau credit monitoring, a credit report and a credit score, with alerts for 24 months from enrollment, plus fraud assistance from Cyberscout, a TransUnion company. Enrollment is at bfs.cyberscout.com/activate with the code printed in the letter, and it must be done within 90 days of the letter's date. Questions go to 1-833-516-6266, Monday to Friday, 8 a.m. to 8 p.m. Eastern Time. A Social Security number does not expire, so a free credit freeze at Equifax, Experian and TransUnion protects for longer than the monitoring does; the guide to credit monitoring offers sets out the difference.

How does this compare with other law firm breaches?

Law firms hold large volumes of other people's data, and 2026 has brought a run of notices from them. The log also has entries for Greenberg Traurig and Fried Frank, and the guide to law firm breach notices compares how firms describe social engineering incidents. Seyfarth's case is narrower than most: the firm says no system was entered, only documents emailed out.

What the record leaves open

• Which clients' employees or matters the documents came from.
• Whether the outside recipient has been identified or the documents recovered.
• How many of the 56,755 live in each state; Indiana is the only record fetched here that gives a total.