Almeida Law Group is investigating a data breach at Cornerstone Staffing Solutions, Inc. The breach occurred on November 6th, 2025. If you were affected, contact Almeida Law Group.
About Cornerstone Staffing Solutions, Inc.
Cornerstone Staffing Solutions, Inc. is a staffing and recruitment agency founded in 2003 and headquartered in Pleasanton, California, with locations across multiple states. The company specializes in light industrial, technology, engineering, logistics, transportation, manufacturing, and sales staffing. Because staffing agencies routinely collect resumes, employment history, Social Security numbers, and other sensitive personal information from job applicants and placed workers, a breach of this kind can create significant exposure for the individuals whose records are held on file.
What Happened?
Cornerstone Staffing Solutions, Inc. was listed in a California Attorney General sample breach notice filed on September 11th, 2026, reporting that a breach occurred on November 6th, 2025. The notice does not specify the number of persons affected, and the text of the breach notification letter was not available for review, so the data types confirmed by the company remain unknown. The approximately ten-month gap between the reported breach date and the California Attorney General filing is notable.
Separately, cybersecurity sources report that the Qilin ransomware group claimed responsibility for attacking Cornerstone Staffing Solutions on its dark web leak site, with that claim first observed on November 13th, 2025. According to reporting by Cybernews and SC Media, Qilin alleged it exfiltrated approximately 300 GB of data, including 120,000 personal resumes and roughly 1 million files. Attacker-published proof samples reportedly appeared to include employee names, job titles, salary details, signed confidentiality documents, internal banking ledgers, banking statements, invoices, and budget records. Cybernews noted that samples also appeared to reference names, Social Security numbers, addresses, email addresses, phone numbers, branch locations, and Employee ID numbers, though Cybernews cautioned that it was unclear whether the personal information belonged to applicants or employees. These data-type claims originate entirely from attacker-published materials and have not been confirmed by Cornerstone Staffing Solutions or any regulator. A federal lawsuit, Hiler v. Cornerstone Staffing Solutions, Inc. (Case No. 5:2026cv02478), has been filed in the U.S. District Court for the Northern District of California and appears connected to this incident, though the specific claims have not been confirmed from available public records.
Key Facts at a Glance
- Company or Organization: Cornerstone Staffing Solutions, Inc.
- Industry: Staffing and Recruitment
- Location: Pleasanton, California (headquarters); 13 office locations across multiple states
- Incident type: Data breach (Qilin ransomware group claimed responsibility)
- Date of breach: November 6th, 2025
- Date of consumer notification: September 11th, 2026
- Litigation status: Hiler v. Cornerstone Staffing Solutions, Inc., Case No. 5:2026cv02478 (N.D. Cal.), filed; specific claims not yet confirmed
- Source: California Attorney General Breach Report; CA AG Breach Notice Letter; Cybernews; SC Media; Justia Dockets
What Should You Do?
If you received a notification from Cornerstone Staffing Solutions, Inc., you should take steps to protect yourself right away. Because the company has not publicly confirmed which types of personal information were exposed, it is prudent to act broadly. Consider placing a fraud alert or credit freeze with each of the three major credit bureaus—Equifax, Experian, and TransUnion—and monitor your credit reports regularly through AnnualCreditReport.com. Review your financial account statements for any unauthorized activity and watch for phishing emails or calls from people claiming to know your personal details. If identity theft occurs, report it at IdentityTheft.gov for a personalized recovery plan.
Your Legal Rights
If your personal information was involved in this breach, you may have legal rights depending on the facts of the incident and the law in your state. Almeida Law Group represents consumers in data breach and privacy litigation and can help you evaluate whether you may have a claim. Contact us at (708) 529-5418 or through our contact page for a free case evaluation.
