CVE-2026-71424 CRITICAL

CVE-2026-71424: Onyx: Cross-user OAuth-token leak via /api/mcp/servers* for per-user MCP servers

Vendor Onyx-Dot-App
Product onyx
Weakness CWE-200 · Info exposure
Published August 17, 2026
Last update August 18, 2026
View on NVD All CVEs

CVSS base score

9.6/10
Attack vector Network
Attack complexity Low
Privileges required Low
User interaction None
Confidentiality High
Integrity High

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N

What the vulnerability does

01Description

Onyx is an open-source AI platform. Prior to 3.1.10, 3.2.14, and 4.0.0, Onyx's GET /api/mcp/servers and GET /api/mcp/servers/persona/{persona_id} endpoints expose another user's OAuth Authorization header because OnyxTokenStorage.set_tokens and OnyxTokenStorage.set_client_info in backend/onyx/server/features/mcp/api.py copy per-user tokens into a shared admin MCPConnectionConfig row and _db_mcp_server_to_api_mcp_server returns that row through auth_template.headers to any BASIC_ACCESS user. This issue is fixed in versions 3.1.10, 3.2.14, and 4.0.0.

Key dates

02Disclosure timeline

August 17, 2026 CVE published
August 18, 2026 Record updated

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