CVE-2026-71424: Onyx-Dot-App Onyx

Critical severity, CVSS 9.6. EPSS: 0.5% chance of exploitation in the next 30 days.

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.

Affected products

• Onyx-Dot-App Onyx: before 3.1.10 (fixed in 3.1.10); from 3.2.0, before 3.2.14 (fixed in 3.2.14); from 3.3.0-beta.0, before 4.0.0 (fixed in 4.0.0)

Published 2026-08-17. Last modified 2026-09-18.