CVE-2026-71424Public exploitNetwork attack vectorHinoki check available

Cross-user OAuth token disclosure via shared config

Published Aug 17, 2026 · Updated Aug 18, 2026

Authorization header disclosure in Onyx before 3.1.10, 3.2.14, and 4.0.0 lets remote authenticated users read another user's OAuth token. In backend/onyx/server/features/mcp/api.py, OnyxTokenStorage.set_tokens and set_client_info copy per-user OAuth data into a shared admin MCPConnectionConfig row, and _db_mcp_server_to_api_mcp_server returns that row's headers in auth_template for GET /api/mcp/servers and GET /api/mcp/servers/persona/{persona_id}. Any authenticated account with BASIC_ACCESS can retrieve the most recently stored bearer token for a per-user OAuth MCP server and then use it against the upstream service as the victim user.

CVSS severity9.6
Critical
EPSS probability0.29%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Authorization header disclosure in Onyx before 3.1.10, 3.2.14, and 4.0.0 lets remote authenticated users read another user's OAuth token. In backend/onyx/server/features/mcp/api.py, OnyxTokenStorage.set_tokens and set_client_info copy per-user OAuth data into a shared admin MCPConnectionConfig row, and _db_mcp_server_to_api_mcp_server returns that row's headers in auth_template for GET /api/mcp/servers and GET /api/mcp/servers/persona/{persona_id}. Any authenticated account with BASIC_ACCESS can retrieve the most recently stored bearer token for a per-user OAuth MCP server and then use it against the upstream service as the victim user.

The record

CVE
CVE-2026-71424
Published
Aug 17, 2026
Updated
Aug 18, 2026
Vendor
Onyx
Product
Onyx
Classifications
CWE-200, CWE-863, T1528
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 17, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 18, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 3.1.10
  2. Affected versionversion=>= 3.2.0, < 3.2.14
  3. Affected versionversion=>= 3.3.0-beta.0, < 4.0.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Onyx · Onyxversion=< 3.1.10; version=>= 3.2.0, < 3.2.14; version=>= 3.3.0-beta.0, < 4.0.0

Published CVSS scores

9.6GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-200Exposure of Sensitive Information to an Unauthorized Actor
CWE-863Incorrect Authorization
T1528Steal Application Access Token

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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