Critical 9.6Published Aug 17, 2026

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

Updated under an hour ago (Oct 27, 2026, 4:00 AM ET)

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Every CVE for onyx-dot-app onyx

Exploited in the last 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.

CVSS: 9.6 CRITICAL (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N
Weakness (CWE): CWE-200, CWE-863
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Deferred
Record last updated: Aug 18, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

onyx-dot-app onyx onyx_dot_app:onyx (from the name)	before 3.1.10; from 3.2.0, < 3.2.14; from 3.3.0-beta.0, < 4.0.0	CNA record

References

References

https://github.com/onyx-dot-app/onyx/security/advisories/GHSA-q62f-rv3h-f822	x-refsource-confirm
https://github.com/onyx-dot-app/onyx/pull/11238	x-refsource-misc
https://github.com/onyx-dot-app/onyx/pull/11242	x-refsource-misc
https://github.com/onyx-dot-app/onyx/pull/11243	x-refsource-misc
https://github.com/onyx-dot-app/onyx/commit/3f3d79d1a7722fdc84a1c61c8aa830d890017e9e	x-refsource-misc
https://github.com/onyx-dot-app/onyx/commit/4001cedd0a8968723bfe95dd188914ed56777910	x-refsource-misc
https://github.com/onyx-dot-app/onyx/commit/b103937888fd5008067c2bb6eb6e5424576394f2	x-refsource-misc
https://github.com/onyx-dot-app/onyx/releases/tag/v4.0.0	x-refsource-misc

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.