Fireworks AI Expands Breach Disclosure to Datasets and Model Weights

What happened

Fireworks AI on November 9, 2026 expanded its disclosure of an October security incident, reporting that attackers accessed account and billing information and, for a limited group of customers, secrets, datasets and incomplete model weights. On October 6, 2026, the company identified unauthorized use of internal credentials and began containment.

At that stage, Fireworks had not detected unauthorized access to customer models, datasets, training data (the material a model is built from), personal information or inference traffic within its security perimeter or control. Customer notifications began on October 7, 2026.

The AI infrastructure provider had initially described the incident as unauthorized use of internal credentials. The affected internal application provided access to resource metadata including identifiers, display names, descriptions and creation times.

Billing information covered billing and shipping addresses, invoice and payment history, account balances and credit usage. Fireworks does not store payment card numbers, which were not affected.

Customers whose data was impacted are receiving account-specific details and recommended responses, and the ongoing investigation may produce additional findings. Development Machines Provided Another Route The update goes beyond Fireworks’ original October 9, 2026 bulletin .

An unauthorized party had accessed environment variables used in evaluation jobs in a limited number of customer accounts. Fireworks rotated employee API (the interface one piece of software uses to talk to another) keys on October 9 and revoked additional user keys and rotated service-account tokens on October 10, 2026.