Nvidia-Backed Fireworks AI Hit by Second Breach in 18 Days

Fireworks AI, a Nvidia-backed startup valued at $17.5 billion, disclosed its second cybersecurity breach in 18 days on Monday — and this one reached customer account and billing information.

The company said in a blog post that the incident occurred on October 24. An unauthorized third party accessed Fireworks' development machines and ran an unauthorized workload affecting customer account and billing data, the startup reported. After detecting the breach, the team closed known critical vulnerabilities. Fireworks said it has not detected further evidence of unauthorized access by the threat actor.

The breach puts at risk relationships with a customer base the company counts at more than 10,000, according to its website.

What did the company say about affected customers?

A Fireworks spokesperson told Bloomberg the company is "actively working with our customers to manage the incident, including Notion, Cursor and others."

The named customers matter. Notion and Cursor are widely used developer and productivity platforms, which means the breach's potential footprint extends well beyond Fireworks' own user base. Fireworks AI, led by CEO and co-founder Lin Qiao, helps developers and enterprises run and scale open-source models — infrastructure that other software products sit on top of.

What happened in the first breach?

This is the second incident in under three weeks. On October 6, according to an earlier Fireworks blog post, an unauthorized third party accessed environment variables used in evaluation jobs. That attack reached a limited number of customer accounts.

The two incidents differ in severity. The October 6 breach touched environment variables in evaluation jobs and a limited set of accounts. The October 24 attack went further, hitting development machines directly and running an unauthorized workload that implicated customer account and billing information — data categories that carry regulatory and financial consequences.

How did Fireworks respond?

According to the company's blog post, the response unfolded in stages:

• Detection of the unauthorized access on its development machines.
• Closure of known critical vulnerabilities after the breach was found.
• A statement that no further evidence of unauthorized access by the threat actor has been detected.
• Active outreach to affected customers, including Notion and Cursor, to manage the incident.

The company has not disclosed, in the material released so far, how the attacker initially gained entry or how many of its 10,000-plus customers had data affected by the October 24 workload.

Why does the $17.5 billion valuation figure into this?

Fireworks AI carries a $17.5 billion valuation and counts Nvidia among its backers. The startup sits in the AI infrastructure layer — running and scaling open-source models for developers and enterprises — which makes it a concentration point for other companies' data and workflows.

Two breaches in 18 days at a company of that valuation and position test customer confidence in a segment where trust is the product. The October 24 attack's reach into billing information, combined with the disclosure that Notion and Cursor are among the affected customers, will likely push Fireworks to release more detail on the attack vector and the scope of data exposed.