HackingProfessional ServicesProfessional ServicesData ExfiltratedCustomer Data InvolvedIdentity (basic)LowContained

CornerStone Staffing Solutions, Inc.

bd_e4dfd8c0234818a1 · schema v1 · pii pii-v2

Severity

Low

Discovered

Nov 17, 2025

Filed

Sep 11, 2026

To disclose

43 weeks

Affected

Not disclosed

Linked

5 filings

Confidence

69%

Full breach record for CornerStone Staffing Solutions, Inc. →

Cornerstone Staffing Solutions, Inc. detected anomalous activity on November 17, 2025, indicating unauthorized access to its network between November 6 and 21, 2025. The investigation found indications that some data may have been removed, though specific files were not determined. Affected data types include names and potentially other personal information. The company engaged a third-party cybersecurity firm, implemented additional security measures, and is offering credit monitoring services.

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California clockDiscovered Nov 17, 2025 → Notified Sep 11, 2026298d ✗ CA 60-day late43 weeks discovery → filing

Incident timeline

undetected · 11 days

discovery → filing · 43 weeks / 298 days

Nov 6, 2025

Begins

Nov 17, 2025

Discovered

Sep 11, 2026

Filed

vs. sector median

+24 wks slower

This filing is one of 5 about the same incident.View merged incident

A leak claim by qilin about this victim predates this filing by 301 days.View originating leak claim

Linked disclosures

Why this link?

Ransomware claims (1)

Leak Siteqilinbd_ec840b7d9ffbec102025-11-13 · +302dVerified by operator

Regulatory filings (3) · sorted by filing gap

Vermont State AGbd_29de5dbb97b766ee2026-09-12 · +1dVerified
Texas State AGbd_d3cf7d86357026862026-09-15 · +4dVerified by operator
Massachusetts State AGbd_22dd62acb7c5bd852026-09-01 · +10dVerified

Name: CornerStone Staffing Solutions, Inc.
norm: cornerstone staffing
Domain: cornerstone-staffing.com

Name: CornerStone Staffing Solutions, Inc.
norm: cornerstone staffing
Domain: cornerstone-staffing.com
Industry: Professional Servicesllm

Discovered: Nov 17, 2025
Breach occurred: Nov 6, 2025 – Nov 21, 2025
Undetected for: 11 daysoccurrence → discovery
Materiality determined: —
Notification sent: Sep 11, 2026
Affected individuals: Not disclosed
Data types: Identity (basic)
Attack vector: Unknown
MITRE ATT&CK: T1041 Exfiltration Over C2 Channel
Threat actor: External

During the incident: Launched an internal investigation
Engaged a third-party cybersecurity firm to contain the threat, support the investigation, and determine the scope of the unauthorized access
Implemented additional security measures
Offering complimentary credit monitoring and identity protection services through HaystackID
Changes made: Implemented additional security measures
Continuing to evaluate ways to further enhance the security of its environment to minimize the likelihood of similar events occurring in the future
Source: Quoted from the filing itself, not independently verified.

Time to disclose: 43 weeks(298 days from discovery to filing)
Compliance flags: CA 60-day late · 298dLeak >180d
Discovery-date grounding: letter-groundedThe discovery date is the detection date narrated in the notification letter — the defensible tier.
Clock breakdown: Statute Window Elapsed Threshold Status
California
Discovered: Nov 17, 2025
→ Notified: Sep 11, 2026
298d 60 days (analyst band, pre-2026 discoveries) CA 60-day late

Statute	Window	Elapsed	Threshold	Status
California	Discovered: Nov 17, 2025 → Notified: Sep 11, 2026	298d	60 days (analyst band, pre-2026 discoveries)	CA 60-day late

Status: No extraction artifact recorded for this disclosure.

Filing propagation · 4 filings · 4 states

View merged incident ↗

Massachusetts State AGSep 1 · first

California State AG+10d · this page

Vermont State AG+11d

Texas State AG+14d

Pattern: first filing Sep 1 (MA), last Sep 15 (TX) — a 14-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://oag.ca.gov/ecrime/databreach/reports/sb24-629595
DisclosureLens links to the originating regulator URL — full filing bodies are not redistributed from public surfaces (§4.5).
Filed at: Sep 11, 2026
Raw hash: 81a0d19661f4ba97cef9e332a0e3c8746193f8615432fa76ba7bc18405b890e3

Linked disclosures

Ransomware claims (1)

Regulatory filings (3) · sorted by filing gap

Reporting entityCornerStone Staffing Solutions, Inc.

Victim entityCornerStone Staffing Solutions, Inc.

Incidentdiscovered Nov 17, 2025

Stated responseLaunched an internal investigation

ComplianceCA 60-day late

Extraction provenanceno artifact recorded

Source provenanceoag.ca.gov