CVE-2026-71424

CRITICAL 9.6

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

CVSS Score

9.6

EPSS Score

0.0%

EPSS Percentile

0th

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.

CWE	CWE-200 CWE-863
Vendor	onyx-dot-app
Product	onyx
Published	Aug 17, 2026

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CVSS v3 Breakdown

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

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Changed

Confidentiality

High

Integrity

High

Availability

None

Affected Versions

onyx-dot-app / onyx

< 3.1.10 >= 3.2.0, < 3.2.14 >= 3.3.0-beta.0, < 4.0.0

References

NVD ↗ CVE.org ↗ EPSS Data ↗