OpenAI experienced a third-party data breach on November 9, 2025, when its vendor, Mixpanel, reported unauthorized access within its own systems.
According to OpenAI’s own disclosure of the incident on November 28, 2025, the attacker exported a dataset containing limited customer identifiable analytics tied to OpenAI API accounts. This led to OpenAI removing Mixpanel from production and beginning its own investigation.
The company noted in its response that the breach happened inside Mixpanel’s environment, not OpenAI’s own. No chat content, API keys, passwords, credentials, or payment data were exposed. The compromised information included names, email addresses, approximate locations, device, and browser details.
OpenAI notified all affected organizations, administrators, and users directly and warned that the most realistic fallout for developers is targeted phishing because attackers have the metadata needed to craft credible messaging.
The Mixpanel notice of security incident provided, “Out of transparency and our desire to share with our community, this blog post contains key information about a recent security incident that impacted a limited number of our customers. On November 8th, 2025, Mixpanel detected a smishing campaign and promptly executed our incident response processes. We took comprehensive steps to contain and eradicate unauthorized access and secure impacted user accounts. We engaged external cybersecurity partners to remediate and respond to the incident.”
The incident did not start inside OpenAI’s own systems but is an example of the effect vendors can have on internal data privacy. Mixpanel wasn’t handling anything sensitive like chat logs or API keys, yet the profile details it held are exactly the kind of breadcrumbs attackers use to launch convincing phishing campaigns.
As more organizations build AI systems on top of third-party analytics and monitoring tools, the risk doesn’t stay in one place anymore. It spreads across every partner and integration, some of which don’t have the same security discipline as the main platform. A breach that looks small on paper can still give attackers a way into broader developer environments, and that ripple effect is what worries teams that depend on OpenAI’s API.
See also: HIPAA Compliant Email: The Definitive Guide (2025 Update)
An API is a structured way for two systems or applications to communicate with each other. It defines how software components request and exchange data so developers can build on top of existing tools without needing to understand their internal code.
Organizations use APIs to connect services, automate workflows, and share data between systems. They help teams move faster because they allow one system’s capabilities to be reused or extended by others.
An endpoint is the specific URL where an API receives a request. It acts like a door into a particular function, such as retrieving a user profile or submitting a form.