HackingPIIGovernment IDMediumActive

Mercadien PC Certified Public Accountants

bd_6a472f77725ed762 · schema v1 · pii pii-v1

Severity

Medium

Discovered

Nov 7, 2025

Filed

Jan 5, 2026

To disclose

8 weeks

Affected

Not disclosed

Linked

12 filings

Confidence

65%

Full breach record for Mercadien PC Certified Public Accountants →

Mercadien PC, a CPA firm, notified the New Hampshire Department of Justice of a data security incident discovered on November 7, 2025. Unauthorized access occurred between September 17 and October 9, 2025. The investigation is ongoing, and the number of affected individuals is currently unknown. Law enforcement was notified, and forensic experts are engaged. Remediation includes password resets and deploying SentinelOne.

J jump to incidentP pin to compareR raw source

Incident timeline

undetected · 51 days

discovery → filing · 8 weeks / 59 days

Sep 17, 2025

Begins

Nov 7, 2025

Discovered

Jan 5, 2026

Filed

This filing is one of 12 filings about the same incident.View merged incident

Linked disclosures

Why this link?

Regulatory filings (10) · sorted by filing gap

Maine State AGbd_be4f63906a17f7282025-12-31 · +5dCandidate
Indiana State AGbd_5a136d8dad7a13462026-02-17 · +43dVerified
Nebraska State AGbd_9581ab095364e27d2026-02-17 · +43dVerified
Delaware State AGbd_b06b2f75cc90e4452026-02-17 · +43dVerified

Show 6 more filings ↓up to 281d gap

South Carolina State AGbd_bb8b76494cae40c62026-02-23 · +49dVerified
Texas State AGbd_7b787e3dbbd82d8e2026-02-24 · +50dVerified
New Hampshire State AGbd_aea05dfcc088a1bf2026-07-20 · +196dVerified
California State AGbd_3c090c1ae9c357382026-10-12 · +280dVerified
Oregon State AGbd_9073a5be3f931a412026-10-12 · +280dVerified
Texas State AGbd_cc54cf6a9eb2d0c22026-10-13 · +281dVerified

Showing first 10 of 11 linked disclosures.

Name: Pierson Ferdinand LLP
norm: pierson ferdinand
Domain: pierferd.com

Name: Mercadien PC Certified Public Accountants
norm: mercadien pc certified public accountants

Discovered: Nov 7, 2025
Breach occurred: Sep 17, 2025 – Oct 9, 2025
Undetected for: 51 daysoccurrence → discovery
Materiality determined: —
Notification sent: Jan 3, 2026
Affected individuals: Not disclosed
Data types: PIIGovernment ID
Data elements: Social Security number
Attack vector: Unauthorized Access
MITRE ATT&CK: T1119 Automated Collection
Threat actor: External
Regulator citations: reported the Incident to law enforcement

During the incident: Reported the Incident to law enforcement
Working with cybersecurity counsel and forensic experts
Password reset
SentinelOne deployed on all machines and scanning
Removing the sensitive information from the impacted system
Changes made: SentinelOne deployed on all machines and scanning
Removing the sensitive information from the impacted system
Source: Quoted from the filing itself, not independently verified.

Time to disclose: 8 weeks(59 days from discovery to filing)
Compliance flags: — (clock not assessable for this source)

Status: No extraction artifact recorded for this disclosure.

Filing propagation · 11 filings · 9 states

View merged incident ↗

Maine State AGDec 31 · first

New Hampshire State AG+5d · this page

Indiana State AG+48d

Nebraska State AG+48d

Delaware State AG+48d

South Carolina State AG+54d

Texas State AG+55d

New Hampshire State AG+201d

California State AG+285d

Oregon State AG+285d

Texas State AG+286d

Pattern: first filing Dec 31 (ME), last Oct 13 (TX) — a 286-day rolling notification. Rolling spreads often mean counsel is filing as thresholds trip per state. Why this link?

Cascade drawn from the first 10 linked disclosures of 11 — the full spread may be wider.

Evidence ladder

Leak-site claim

Attacker assertion only. Establishes: claim date, group, alleged victim.

Press / market report

Unlocks: incident narrative, operational impact. Still no compliance clock.

State AG / regulator filingThis record

Unlocks: discovery date, data types, affected count, compliance clock.

SEC 8-K / victim statement

Unlocks: materiality, stated response, full audit trail. Ceiling removed.

Source URL: https://mm.nh.gov/files/uploads/doj/remote-docs/mercadien-certified-public-accountants-20260105.pdf
DisclosureLens links to the originating regulator URL — full filing bodies are not redistributed from public surfaces (§4.5).
Filed at: Jan 5, 2026
Raw hash: 1bfd3834caae3f4128f3835bbbf38e042e5a59e8e35748d994ad721a5a5ed7bf

Linked disclosures

Regulatory filings (10) · sorted by filing gap

Reporting entityPierson Ferdinand LLP

Victim entityMercadien PC Certified Public Accountants

Incidentdiscovered Nov 7, 2025

Stated responseReported the Incident to law enforcement

Complianceclock not assessable

Extraction provenanceno artifact recorded

Source provenancemm.nh.gov