CVE intelligence and bounded remediation

CVE-2026-41487 — Langfuse is an open source large language model engineering platform

Medium CVSS 5.4

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.

Severity
Medium
CVSS
5.4 (3.1)
Published
2026-05-08
CISA KEV
Not currently listed
Ecosystem
software/application
Weaknesses
CWE-284

Affected products

  • langfuse / langfuse

Matched remediation archetype

Authorization bypass, IDOR, and cross-tenant access

This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.

Check exposure

  • Map object and action authorization checks across API, UI, batch, import/export, and background-job paths.
  • Identify tenant, ownership, role, and policy boundaries for affected resources and administrative operations.
  • Use synthetic fixtures to compare intended access matrices without accessing another user's real data.

Remediate safely

  • Enforce server-side authorization at each resource access and state transition using the authenticated principal and trusted tenant context.
  • Scope data queries by tenant and ownership; treat client-supplied identifiers, roles, and policy claims as untrusted.
  • Add deny-by-default policy tests for horizontal and vertical access across every affected transport.

Authoritative sources

Complete CVE record and remediation plan

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