HackingTechnologyInformationDelayed DiscoveryCustomer Data InvolvedIdentity (basic)Government IDPIIMediumContained

MASTEC, INC.

bd_fa5d678c3d216037 · schema v1 · pii pii-v1

Severity

Medium

Discovered

Oct 1, 2025

Filed

Jun 9, 2026

To disclose

36 weeks

Affected

142state residents only

Linked

9 filings

Confidence

65%

Full breach record for MASTEC, INC. →2 incidents on file

MasTec, Inc. disclosed a data breach in Massachusetts (filing 2026-932) affecting at least 73 Rhode Island residents, with notifications sent to individuals in multiple states. The incident occurred in August 2025, involving unauthorized access to a portion of the network. Personal information was accessed, and MasTec offered credit monitoring services.

J jump to incidentP pin to compareR raw source

Massachusetts clock✗ MA AG >90d36 weeks discovery → filing

Incident timeline

undetected · 61 days

discovery → filing · 36 weeks / 251 days

Aug 1, 2025

Begins

Oct 1, 2025

Discovered

Jun 9, 2026

Filed

vs. sector median

+17 wks slower

This filing is one of 9 about the same incident.View merged incident

Linked disclosures

Why this link?

Ransomware claims (1)

Leak Sitecl0pbd_077ee15e6166ed792025-10-31 · +220dVerified by operator

Regulatory filings (7) · sorted by filing gap

Texas State AGbd_2db96186099527c32026-06-09Verified
Vermont State AGbd_17006039c927389d2026-06-05 · +4dVerified
Indiana State AGbd_2337a1feed74d7a42026-06-05 · +4dVerified
Nebraska State AGbd_69df7fd6f827f7472026-06-05 · +4dVerified

Show 3 more filings ↓up to 5d gap

Maine State AGbd_b14ee6c6db7a57262026-06-05 · +4dVerified
South Carolina State AGbd_d93b0d10e9a7baae2026-06-05 · +4dVerified
New Hampshire State AGbd_9a55bbe733ae71cb2026-06-04 · +5dCandidate

Name: MASTEC, INC.
norm: mastec
Domain: mastec.com

Name: MASTEC, INC.
norm: mastec
Domain: mastec.com
Industry: Technologyllm

Discovered: Oct 1, 2025
Breach occurred: Aug 1, 2025 – Aug 31, 2025
Undetected for: 61 daysoccurrence → discovery
Materiality determined: —
Notification sent: May 11, 2026
Affected individuals: 142state-resident count only
Data types: Identity (basic)Government IDPII
Attack vector: Unauthorized Access
MITRE ATT&CK: T1190 Exploit Public-Facing Application
Threat actor: External
Initial access: exploit_public_facing

During the incident: Worked with third-party cybersecurity experts to investigate and remediate
Engaged a data-review firm to analyze files' contents
Notified law enforcement
Changes made: Further secured systems to protect information
Source: Quoted from the filing itself, not independently verified.

Time to disclose: 36 weeks(251 days from discovery to filing)
Compliance flags: MA AG >90dLeak >180d
Discovery-date grounding: letter-groundedThe discovery date is the detection date narrated in the notification letter — the defensible tier.

Status: No extraction artifact recorded for this disclosure.

Filing propagation · 8 filings · 8 states

View merged incident ↗

New Hampshire State AGJun 4 · first

South Carolina State AG+1d

Texas State AG+5d

Massachusetts State AG+5d · this page

Pattern: first filing Jun 4 (NH), last Jun 9 (MA) — a 5-day rolling notification. Rolling spreads often mean counsel is filing as thresholds trip per state. Why this link?

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://www.mass.gov/doc/2026-932-mastec/download
DisclosureLens links to the originating regulator URL — full filing bodies are not redistributed from public surfaces (§4.5).
Filed at: Jun 9, 2026
Raw hash: ff5bba25c98ab12ff0754ae5e14e088ee56b6ed98a6b2ea9c9a40de1e2c62093

Linked disclosures

Ransomware claims (1)

Regulatory filings (7) · sorted by filing gap

Reporting entityMASTEC, INC.

Victim entityMASTEC, INC.

Incidentdiscovered Oct 1, 2025

Stated responseWorked with third-party cybersecurity experts to investigate and remediate

ComplianceMA AG >90d

Extraction provenanceno artifact recorded

Source provenancewww.mass.gov