Fireworks AI expands October breach disclosure: billing data, datasets and incomplete model weights were accessed

On November 9, 2026, Fireworks AI updated its October 2026 security bulletin: the investigation has found wider impact than the company first reported. When the first bulletin was published on October 9, only Fireworks stored secrets (for example, secrets used in evaluation jobs) were known to have been accessed. Since then, Fireworks discovered impacts to account and billing information and, for a limited set of accounts, also to secrets, datasets and incomplete models (model weights). The company says its investigation is ongoing and may reveal additional information.

Fireworks says a third-party cloud provider that hosted its R&D machines experienced a security incident on October 23, 2026, and that on October 24 the unauthorized party used it to reach Fireworks development machines and run an unauthorized workload, which led to additional customer data impact. The affected internal application provided access to resource metadata (resource identifiers, display names, descriptions, creation times) and billing information (billing and shipping addresses, invoice and payment history, account balances and credit usage). Payment card numbers are not stored by Fireworks and were not impacted.

Fireworks links the evidence to a financially motivated cybercriminal group aimed at selling tokens from unauthorized access to large language models through illicit routing gateways, known as LLMJacking. It says it detected the October 24 activity the same day, has not detected further successful unauthorized access on the platform customers use since October 25, and has not detected any impact to Inference, Training SDK or Nexus, which are zero data retention by default. Fireworks notified law enforcement, is working with Palo Alto Networks Unit 42, revoked and replaced credentials and service accounts, and has disabled self-serve dataset uploads and downloads used by Batch Inference and dataset-based training while it investigates. Affected customers are being notified with account-specific details and recommended actions.