MasTec Data Breach: 25,220 Individuals Affected

MasTec Inc., a leading infrastructure engineering and construction company headquartered in Coral Gables, Florida, disclosed a data breach that affected approximately 25,220 individuals in the United States, including 1,160 South Carolina residents and 11 Maine residents

The breach was disclosed to attorneys general in Maine and South Carolina on June 5, 2026. MasTec began sending written notifications to affected consumers on May 11, 2026.

In early October 2025, MasTec received reports of suspicious activity on its network and began working with third-party cybersecurity experts to investigate. Later that same month, the investigation confirmed that an unauthorized third party had gained access to a limited section of the company's computer systems during those few days in August.

On Oct. 29, 2025, the CL0P ransomware group posted on the Tor network, claiming to have obtained sensitive data from MasTec.

After identifying the files that were affected by the breach, MasTec hired a separate data-review firm to examine their contents. The company received the results of that review in early February 2026.

Affected individuals received a personalized letter identifying the specific types of personal information that were exposed in their case; however, the publicly available version of the consumer notice does not list the exact categories of data involved but may include information such as names, Social Security numbers, dates of birth, financial information and more.

MasTec's response to the breach

MasTec is offering affected individuals a free membership to Financial Shield, a credit and identity-theft monitoring service. The length of the membership was personalized in each individual's letter.

To enroll, recipients were directed to visit the Financial Shield enrollment website and enter a personalized activation code included in their notification letter. Each letter also contained a specific deadline by which the recipient must enroll to activate the service.

For individuals who prefer not to enroll online or who have questions about the breach, MasTec set up a dedicated response line at 844-953-0840.