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CVE-2026-71424

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

Published: Aug 17, 2026Updated: Aug 18, 2026 Sources: CVE List NVDCWE-200
9.6CRITICAL
NVD MITRE
EPSS Score
0.3%
Top 78.9%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
No Fix Available
Self-Check
Not available

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.

No summary for this CVE yet.

CVSS Vector Breakdown

AV:NAC:LPR:LUI:NS:CC:HI:HA:N
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:LPrivileges Required
Low
UI:NUser Interaction
None
Scope
S:CScope
Changed
Impact
C:HConfidentiality
High
I:HIntegrity
High
A:NAvailability
None
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Weaknesses

CWE-200CWE-863

Affected Products

onyx-dot-app
aka onyx
onyxOn-prem
Web & CMS Plugins / site-builder

Exploitability

No known exploits, KEV entries, or remediation guidance available for this vulnerability yet.
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Attack Graph

Products CVE Techniques Tactics

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MITRE ATT&CK

3 techniques
Collection
Initial Access
View detailed technique mapping

References

https://github.com/onyx-dot-app/onyx/security/advisories/GHSA-q62f-rv3h-f822
github.com
https://github.com/onyx-dot-app/onyx/pull/11238
github.com
https://github.com/onyx-dot-app/onyx/pull/11242
github.com
and 5 more references View all →

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