Langfuse Cross-Organization Member and Invitation Enumeration Vulnerability

A vulnerability in Langfuse, an open-source large language model engineering platform, allows authenticated users to enumerate names and email addresses of members in other organizations via certain project membership APIs. This issue is present in Langfuse versions 2.70.0 prior to 2.95.11 and 3.124.1, and arises because the server improperly trusted user-controlled organization IDs in authorization checks. While no sensitive customer data is exposed, the vulnerability could be exploited by internal users in self-hosted deployments without an SSO provider, to access lists of other internal users.

Impact

Successful exploitation of this vulnerability could lead to unauthorized disclosure of names and email addresses of organization members or invitees, allowing for potential phishing attacks or other social engineering tactics.

Reproduction

To reproduce this vulnerability, an authenticated user must know the target organization's ID and use it to request member or invitation data from the project's membership APIs. This can be done by changing the organization ID in the API request to that of the target organization, while including the necessary authentication token.

Remediation

Users can upgrade to Langfuse versions 2.95.11 or 3.124.1 to address this vulnerability. Instructions for downloading these versions are available on the Langfuse GitHub Releases page.