CVE-2026-71424
Onyx: Cross-user OAuth-token leak via /api/mcp/servers* for per-user MCP servers
- State
- Published
- Severity
- 9.6 Critical
- Published
- Aug 17, 2026
- Updated
- Aug 18, 2026
- Reserved
- Aug 6, 2026
Description
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 9.6 Critical | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N | GitHub_M |
Weaknesses
Affected Products
| Product | Versions |
|---|---|
onyxonyx-dot-app |
|
References
- https://github.com/onyx-dot-app/onyx/security/advisories/GHSA-q62f-rv3h-f822
- https://github.com/onyx-dot-app/onyx/pull/11238
- https://github.com/onyx-dot-app/onyx/pull/11242
- https://github.com/onyx-dot-app/onyx/pull/11243
- https://github.com/onyx-dot-app/onyx/commit/3f3d79d1a7722fdc84a1c61c8aa830d890017e9e
- https://github.com/onyx-dot-app/onyx/commit/4001cedd0a8968723bfe95dd188914ed56777910
- https://github.com/onyx-dot-app/onyx/commit/b103937888fd5008067c2bb6eb6e5424576394f2
- https://github.com/onyx-dot-app/onyx/releases/tag/v4.0.0
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