---
id: CVE-2026-85700
title: >-
  Onyx 4.6.6 fails to properly restrict access to custom tool credentials stored
  in custom_headers, allowing any authenticated user to read admin-defined API
  keys
summary: >-
  Onyx 4.6.6 fails to properly restrict access to custom tool credentials stored
  in custom_headers, allowing any authenticated user to read admin-defined API
  keys. Attackers with basic authentication can call GET /tool/{tool_id} or GET
  /to…
severity: medium
cvss: 6.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N'
cwe:
  - CWE-522
published: '2026-09-04'
updated: '2026-09-23'
sourceUpdated: '2026-09-23T17:17:45.033'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-85700'
references:
  - url: 'https://github.com/onyx-dot-app/onyx'
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/onyx-dot-app/onyx/blob/v4.6.6/backend/onyx/server/features/tool/api.py
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/onyx-dot-app/onyx/blob/v4.6.6/backend/onyx/server/features/tool/models.py
    label: disclosure@vulncheck.com
  - url: 'https://github.com/onyx-dot-app/onyx/issues/13165'
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/onyx-4.6.6-custom-tool-secret-header-disclosure-via-tool-endpoints
    label: disclosure@vulncheck.com
tags:
  - nvd
epss: 0.00511
epssPercentile: 0.411
ingestedAt: '2026-09-23T17:28:14.826Z'
---

## Overview

Onyx 4.6.6 fails to properly restrict access to custom tool credentials stored in custom_headers, allowing any authenticated user to read admin-defined API keys. Attackers with basic authentication can call GET /tool/{tool_id} or GET /tool endpoints to retrieve plaintext authorization headers and third-party API credentials, then use them to directly access upstream APIs.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.