OpenAI disclosed a security incident on November 26, 2025, involving Mixpanel, a third-party analytics provider that handled web analytics for the company’s API platform. The breach exposed limited user profile data from API accounts but did not compromise OpenAI’s core systems, ChatGPT, or sensitive credentials. Here’s what happened, who’s affected, and what you need to do.
What Happened in the OpenAI Mixpanel Incident
The OpenAI Mixpanel incident originated from a targeted smishing campaign, a form of phishing attack delivered via SMS text messages. An attacker gained unauthorized access to Mixpanel’s systems and successfully exported a dataset containing limited customer information and analytics data.
Timeline of the Security Breach
The incident unfolded over several weeks with the following key dates:
- November 8, 2025: Mixpanel detected the smishing campaign targeting an employee account and activated incident response protocols
- November 9, 2025: Mixpanel confirmed unauthorized access to part of their systems and notified OpenAI of the ongoing investigation
- November 25, 2025: Mixpanel shared the complete affected dataset with OpenAI for review
- November 26-27, 2025: OpenAI began notifying impacted organizations, administrators, and individual API users via direct email
How the Attack Occurred (Smishing Campaign)
According to Mixpanel CEO Jen Taylor, the breach originated from a smishing campaign that successfully compromised an employee account. Smishing, or SMS phishing, tricks targets into revealing credentials or clicking malicious links through text messages. Once inside Mixpanel’s environment, the attacker exported analytics data tied to OpenAI’s API platform usage.
Importantly, this was not a breach of OpenAI’s infrastructure; the attack was entirely contained within Mixpanel’s systems.
What Data Was Exposed in the Mixpanel Breach
The compromised dataset contained analytics-level information associated with accounts on platform.openai.com, the frontend interface for OpenAI’s API product.
User Information at Risk
The following data points may have been included in the exported dataset:
- API account names
- Email addresses associated with API accounts
- Approximate coarse location based on browser data (city, state, country)
- Operating system and browser details
- Referring websites
- Organization or user IDs associated with API accounts
This type of metadata could potentially enable phishing attempts or credential stuffing attacks against affected users.
What Was NOT Compromised
OpenAI emphasized that several categories of sensitive data remained secure:
- Chat content, prompts, or responses
- API requests or API usage data
- Passwords or credentials
- API keys
- Session tokens or authentication tokens
- Payment details or financial information
- Government-issued IDs
- Any ChatGPT account information
The breach affected only metadata from the API platform frontend, not operational or transactional data.
Who Is Affected by the Incident
The scope of the breach was limited to a specific subset of OpenAI’s user base.
API Users vs ChatGPT Users
Only users who accessed OpenAI’s API platform (platform.openai.com) may have been affected. ChatGPT users and consumers of other OpenAI products were not impacted by this incident. OpenAI has not disclosed the exact number of affected API customers.
How to Check If You’re Impacted
OpenAI is directly notifying all affected organizations, administrators, and individual users through official email communications. If you use the OpenAI API and haven’t received a notification by early December 2025, your account was likely not included in the compromised dataset. However, you should still review your account activity and monitor for suspicious emails or login attempts.
How OpenAI and Mixpanel Responded
Both companies took immediate action following the discovery of the breach.
OpenAI’s Immediate Actions
OpenAI’s response included several security measures:
- Removed Mixpanel from all production services immediately
- Conducted a comprehensive review of the affected dataset
- Initiated direct communication with all impacted users
- Terminated the business relationship with Mixpanel
- Launched broader vendor security audits across the supply chain
- Implemented continuous monitoring for potential data misuse
Industry experts praised OpenAI’s swift decision to terminate its Mixpanel contract as a strong security signal.
Mixpanel’s Security Measures
Mixpanel deployed multiple containment and remediation actions:
- Secured all affected user accounts
- Revoked active sessions and sign-ins across the platform
- Rotated compromised credentials for impacted accounts
- Blocked malicious IP addresses identified in the attack
- Registered indicators of compromise (IOCs) in their SIEM platform
- Performed global password resets for all Mixpanel employees
- Engaged external cybersecurity partners for forensic analysis and incident response
Understanding Third-Party Vendor Risks
The OpenAI Mixpanel incident highlights a growing cybersecurity challenge: inherited risk from trusted vendors.
Why Vendor Breaches Are Rising
Third-party vendors have become a preferred attack vector for cybercriminals. Research shows that approximately 20% of data breaches are linked to third parties, often resulting in greater financial losses due to reputational damage and business disruption. The average cost of a breach affecting multiple environments reaches $4.88 million.
Nearly two-thirds of organizations have experienced data breaches through lax third-party security systems, according to the Ponemon Institute. Vendors often have direct access to sensitive internal systems and customer data, creating a gateway for attackers who successfully compromise vendor security.
The Supply Chain Security Problem
This incident demonstrates that even companies with robust internal security can be exposed through their vendor ecosystem. Common vulnerabilities in third-party tools include unpatched software, weak access controls, and inadequate data handling practices. Organizations must implement continuous monitoring of vendor security postures, as one-time audits cannot detect evolving risks.
What You Should Do Now
If you’re an OpenAI API user, take these immediate security steps.
Security Steps for Affected Users
Follow these recommendations to protect your account:
- Monitor your official email for communications from OpenAI (security@openai.com)
- Review your API account activity for any unauthorized access or unusual patterns
- Be vigilant against phishing attempts using the exposed information (name, email, organization ID)
- Do not click links in unsolicited emails claiming to be from OpenAI verify directly through platform.openai.com
- Enable additional security measures like two-factor authentication if available
- Watch for credential stuffing attempts on other platforms where you use the same email address
Best Practices for API Security
Developers and organizations should adopt these long-term security practices:
- Use OAuth token-based authentication with expiration policies (e.g., 24-hour token lifespans)
- Implement least-privilege access controls and limited scopes for API tokens
- Regularly rotate credentials and API keys on a scheduled basis
- Maintain an inventory of all third-party services with access to your systems
- Require vendors to validate their security processes and assume liability in contracts
- Deploy continuous monitoring tools to track third-party security postures
- Always validate and sanitize input from endpoints before passing to other endpoints
Comparison Tables: What Was Exposed Vs What Remained Secure
| Compromised Data | Secure Data (NOT Exposed) |
|---|---|
| API account names | Chat content and prompts |
| Email addresses | API requests and usage data |
| Approximate location (city/state/country) | Passwords and credentials |
| Operating system and browser details | API keys |
| Referring websites | Session and authentication tokens |
| Organization/user IDs | Payment and financial details |
| – | Government-issued IDs |
| – | ChatGPT account data |
OpenAI Mixpanel Incident vs Other Major Third-Party Breaches
| Incident | Attack Vector | Data Exposed | Response Time |
|---|---|---|---|
| OpenAI-Mixpanel (Nov 2025) | Smishing campaign | Limited analytics metadata | 17 days (detection to notification) |
| Telecom vendor breach (Jan 2023) | Third-party access vulnerability | 40M+ customer records | Not disclosed |
| General third-party breaches | Various (unpatched software, weak access) | Varies widely | Often delayed discovery |
PROS & CONS
OpenAI’s Response: Strengths
Swift vendor termination – OpenAI immediately ended its Mixpanel contract, signaling strong security commitment
Transparent communication – The company proactively notified all potentially affected users with detailed information
Limited scope – The breach was contained to analytics metadata, not operational or sensitive data
Expanded audits – OpenAI initiated broader vendor security reviews across its supply chain
No core systems compromised – OpenAI’s infrastructure and ChatGPT remained completely secure
Incident & Vendor Management: Weaknesses
17-day disclosure gap – Users weren’t notified until 17 days after the initial discovery (Nov 9 to Nov 26)
Third-party dependency – Reliance on external vendors created inherited security risk
Phishing risk created – Exposed email addresses and metadata enable targeted phishing campaigns
Unknown affected count – OpenAI has not disclosed the total number of impacted API users
Smishing success – The attack exploited human vulnerability rather than technical flaws
Incident Technical Details
Attack Type: SMS phishing (smishing) campaign targeting Mixpanel employee credentials
Affected System: Mixpanel analytics environment (not OpenAI infrastructure)
Affected Platform: platform.openai.com (OpenAI API frontend only)
Attack Timeline:
- Detection: November 8, 2025
- Initial notification: November 9, 2025
- Dataset sharing: November 25, 2025
- User notification: November 26-27, 2025
Data Categories Exposed:
- PII: Names, email addresses, approximate locations
- Technical metadata: OS/browser details, referring URLs
- Identifiers: Organization IDs, user IDs
Data Categories Secured:
- Authentication: Passwords, API keys, session tokens
- Operational: API requests, usage data, chat content
- Financial: Payment details, transaction data
- Compliance: Government IDs, sensitive credentials
Containment Measures Deployed:
- Session revocation across affected accounts
- Credential rotation for compromised accounts
- IP blocking of malicious addresses
- Global employee password resets
- Vendor contract termination
Forensic Analysis:
- External cybersecurity partners engaged
- IOC registration in SIEM platform
- Authentication and export log reviews
Featured Snippet Boxes
What is the OpenAI Mixpanel incident?
The OpenAI Mixpanel incident was a security breach discovered on November 8-9, 2025, where attackers used a smishing campaign to access Mixpanel’s systems and export limited analytics data from OpenAI’s API platform. The breach exposed basic user profile information like names, emails, and browser details for some API users, but did not compromise passwords, API keys, or ChatGPT accounts.
What data was exposed in the Mixpanel breach?
The exposed data included API account names, email addresses, approximate locations (city/state/country), operating system and browser details, referring websites, and organization/user IDs. No passwords, API keys, chat content, payment details, or government IDs were compromised.
Are ChatGPT users affected by the Mixpanel incident?
No, ChatGPT users were not affected by the Mixpanel incident. The breach only impacted users who accessed OpenAI’s API platform (platform.openai.com). All ChatGPT accounts, chat content, and consumer-facing OpenAI products remained secure.
What is a smishing attack?
Smishing (SMS phishing) is a cyberattack method that uses text messages to trick targets into revealing credentials, clicking malicious links, or downloading harmful content. In the Mixpanel incident, attackers used smishing to compromise an employee account and gain unauthorized system access.
How did OpenAI respond to the Mixpanel breach?
OpenAI immediately removed Mixpanel from all production services, reviewed the compromised dataset, terminated its contract with Mixpanel, and began directly notifying all affected users. The company also launched broader vendor security audits and implemented continuous monitoring for potential data misuse.
What should OpenAI API users do after the Mixpanel incident?
API users should monitor official emails from OpenAI, review account activity for unauthorized access, stay vigilant against phishing attempts using exposed information, enable two-factor authentication where available, and avoid clicking links in unsolicited emails claiming to be from OpenAI.
Source: OpenAI
