Middlesex Sheriff's Office: 19,080 individuals, Jan 2026.

OCR classifies the incident as a hacking or IT incident, with the breached information held in a network server. Hacking/IT Incident is the type recorded on 154 of the 245 Massachusetts filings (63%) and on 85% of all filings submitted in 2026. Network Server is the most common location in the state, appearing on 52% of Massachusetts filings.

No business associate is recorded on the filing; 37% of Massachusetts filings do involve one. At 19,080 individuals the breach is 4.7 times the Massachusetts median filing of 4,049 and 4.8 times the national median of 4,000 across all 8,012 filings. It sits in the 10,000 to 99,999 band, which holds 1,973 filings.

As of 8 October 2026 the case is listed by HHS OCR under Cases Currently Under Investigation. OCR has not published a closing summary, so this page is limited to the fields on the filing itself; the archive entry that follows a closed investigation usually adds a short account of what was exposed and what the entity did afterwards.

Massachusetts's breach notification statute (Mass. Gen. Laws ch. 93H) requires notice to affected residents as soon as practicable and without unreasonable delay. Its attorney general threshold: all breaches (AG and Office of Consumer Affairs and Business Regulation). The HIPAA Breach Notification Rule ran alongside it: notice to affected individuals and to HHS without unreasonable delay and no later than 60 days after discovery, which is the clock that put this filing on the portal.

Multiplying 19,080 individuals by IBM's $160 customer-PII cost per record (Cost of a Data Breach 2025, the figure the site's calculator uses) gives a modelled $3.05M; the 2026 edition's $192 gives $3.66M. Both are modelled estimates with the method shown, not costs disclosed by Middlesex Sheriff's Office. For scale, IBM's 2026 average cost of a healthcare breach is $6.64M, so this filing models at 0.6 times the sector average.