CVE-2026-41487: Langfuse LLM connection update flaw exposes stored provider API key

Summary

Langfuse versions from 3.68.0 up to, but not including, 3.167.0 contain a role-based access control flaw in the LLM connection update flow. An authenticated user with the "member" role in a project can point an existing LLM connection at an attacker-controlled baseUrl, causing Langfuse to reuse the stored provider secret and send the test request to that endpoint, which could expose the plaintext provider LLM API key. The attack requires that the user already belongs to the project with "member" scoped access.

Mitigation

This issue has been patched in version 3.167.0.

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