The company confirmed the incident in a security bulletin posted to its website. The latest breach follows a separate incident identified on Oct. 6, making this the company’s second known intrusion in roughly five weeks.
What Happened on October 24
An unauthorized third party used a security incident at an external cloud provider to reach Fireworks development machines and run an unauthorized workload.
Fireworks detected the activity on Oct. 24 and says it closed known critical vulnerabilities the same day. The company’s security bulletin reports no evidence of successful unauthorized access to its customer-facing platform after Oct. 25. The investigation remains ongoing.
What the Attackers Reached
Billing records, secrets, and partial model weights were among the data categories accessed.
Account and billing information accessed in the breach includes billing and shipping addresses, invoice and payment history, account balances, and credit usage. The company does not store payment-card numbers, so card data was not affected.
For a limited set of accounts, attackers accessed secrets, datasets, and incomplete model weights. Fireworks said its Inference, Training SDK, and Nexus products are zero-data-retention by default and showed no detected impact.
How This Breach Differs From the First
The Oct. 6 incident involved misused internal credentials; the second entered through a third-party cloud environment before reaching development systems.
In the first incident, attackers exploited internal Fireworks credentials. That access reached environment variables, including API keys and tokens, inside evaluation jobs tied to a limited number of customer accounts.
Fireworks said at the time that it found no evidence of access to customer models, datasets, training data, personal information, or inference traffic within its security perimeter. The second breach took a different path, entering via an external provider before reaching development infrastructure. Bloomberg reported that Fireworks disclosed the second incident to customers on Nov. 9 and that tens of thousands of files contained customer data in some cases. According to Bloomberg, Fireworks confirmed it is working with affected customers, including Notion and Cursor.
What Fireworks Is Doing About It
The company revoked compromised credentials, isolated affected systems, and obtained assistance from Palo Alto Networks’ Unit 42 for forensic analysis and security hardening.
The company revoked and replaced compromised credentials and service-account tokens and restricted unauthorized network paths. It also isolated affected systems and tightened controls around data storage and analytics.
Fireworks engaged Palo Alto Networks’ Unit 42 incident-response division for forensic analysis and ongoing security hardening. Customers whose data was affected are being notified directly with recommended response actions, though the company cautions that the investigation may reveal additional information.
The Larger Problem This Exposes
A compromised unauthorized third party cloud environment can provide an indirect access path into a company’s development infrastructure even when production systems remain intact.
AI infrastructure providers hold assets well beyond standard account records. Model weights, datasets, secrets, and confidential files exposed carry real confidentiality and intellectual-property risk for affected customers. Until Fireworks’ investigation concludes, the full scope of what was accessed remains unclear.
