CVE-2026-41487: Langfuse: Improper role-based-access control in Langfuse LLM connection management allowed users of role “member” to retrieve stored LLM provider API keys

Severity: medium (CVSS 5.4 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-05-08 · updated 2026-06-17
Weakness: CWE-284

Description

Langfuse is an open source large language model engineering platform. From version 3.68.0 to before version 3.167.0, there is a role-based-access control flaw in the LLM connection update flow. An authenticated, low-privileged user of role “member” in a project could request the update of an existing LLM connection to an attacker-controlled baseUrl, causing Langfuse to reuse the stored provider secret and redirect the test request to an attacker-controlled endpoint. This could expose the plaintext provider LLM API key for that connection. The attack is only possible if a user is already part of a project and has “member” scoped access. This issue has been patched in version 3.167.0.

Affected products

langfuse: from 3.68.0 before 3.167.0 — fixed in 3.167.0

How to fix

Upgrade to a fixed version: langfuse 3.167.0. Check the vendor advisory for mitigations.

References

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