Onyx: Cross-user OAuth-token leak via /api/mcp/servers* for per-user MCP servers
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Information disclosure, Security bypass
- Confidentiality · integrity · availability
- High · High · None
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-200 and CWE-863.
Summary
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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| onyx-dot-app | onyx | before 3.1.10; 3.2.0 to before 3.2.14; 3.3.0-beta.0 to before 4.0.0 | 3.1.10, 3.2.14, 4.0.0 | Patch available | CNA |
- onyx Vendoronyx-dot-app Affected before 3.1.10; 3.2.0 to before 3.2.14; 3.3.0-beta.0 to before 4.0.0 Fixed in 3.1.10, 3.2.14, 4.0.0 Patch available CNA
Remediation
- Fix · CNA onyx (onyx-dot-app) Fixed in 3.1.10, 3.2.14, 4.0.0
Timeline
- 2026-10-02 Threatist record created from CVE-2026-71424
References
Other 8
- 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
More onyx-dot-app vulnerabilities
- TI-2026-58811 Onyx 4.6.6 Custom Tool Secret Header Disclosure via Tool Endpoints CVSS 4.0HIGH 7.1
- TI-2026-45084 Authorization bypass in onyx-dot-app onyx CVSS 3.1MEDIUM 6.5
- TI-2026-80125 Cross-site scripting in onyx-dot-app Onyx PreviewTab.tsx CVSS 4.0MEDIUM 5.1
Sources
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences