---
id: CVE-2026-90898
title: Bifrost registers MCP clients through its management API
summary: >-
  Bifrost registers MCP clients through its management API. A stdio client is a
  command plus args. Bifrost starts that program in the gateway the moment the
  client is added. No MCP handshake required.




  The default is governance.auth_conf…
severity: critical
cvss: 9.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-284
  - CWE-306
vendor: maximhq
product: github.com/maximhq/bifrost/transports
affected:
  - github.com/maximhq/bifrost/transports < 2.1.0
published: '2026-09-14'
updated: '2026-09-18'
sourceUpdated: '2026-09-18T19:31:11.370'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-90898'
references:
  - url: 'https://github.com/maximhq/bifrost'
    label: reefs@jfrog.com
  - url: >-
      https://github.com/maximhq/bifrost/commit/12e170352bd25eab1ae9ba16611f1797d1fd8fdc
    label: reefs@jfrog.com
  - url: 'https://github.com/maximhq/bifrost/pull/6757'
    label: reefs@jfrog.com
  - url: 'https://github.com/maximhq/bifrost/releases/tag/transports/v2.1.0'
    label: reefs@jfrog.com
tags:
  - nvd
  - cve.org
  - exploit-available
epss: 0.00343
epssPercentile: 0.27967
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: total
  timestamp: '2026-09-14T11:01:44.207374Z'
ingestedAt: '2026-09-14T15:23:07.462Z'
exploits:
  github: 1
  githubRepos:
    - 'https://github.com/HORKimhab/CVE-2026-90898'
  checkedAt: '2026-09-24T07:53:24.966Z'
exploitAvailable: true
---

## Overview

Bifrost registers MCP clients through its management API. A stdio client is a command plus args. Bifrost starts that program in the gateway the moment the client is added. No MCP handshake required.



The default is governance.auth_config.is_enabled=false. Auth off means every caller is a local admin. One unauthenticated POST /api/mcp/client is enough to run a program as the Bifrost process user (appuser on the official image).



 transports/v2.1.0 refuses an unauthenticated stdio registration with 403. transports/v2.0.0 still allows it.

## Remediation

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