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    CVE-2026-90898

    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.

    Published:Sep 14, 2026
    Last Modified:Sep 14, 2026
    EPS:Sep 14, 2026
    EPSS Score:
    CVSS Score:9.8

    Affected Products

    Vendor
    Maximhq
    Product
    Bifrost

    Exploits

    https://github.com/HORKimhab/CVE-2026-90898

    Common Attack Pattern Enumeration and Classification (CAPEC)

    CAPEC-12 Choosing Message Identifier
    CAPEC-166 Force the System to Reset Values
    CAPEC-19 Embedding Scripts within Scripts
    CAPEC-216 Communication Channel Manipulation
    CAPEC-36 Using Unpublished Interfaces or Functionality
    CAPEC-441 Malicious Logic Insertion
    CAPEC-478 Modification of Windows Service Configuration
    CAPEC-479 Malicious Root Certificate
    CAPEC-502 Intent Spoof
    CAPEC-503 WebView Exposure
    CAPEC-536 Data Injected During Configuration
    CAPEC-546 Incomplete Data Deletion in a Multi-Tenant Environment
    CAPEC-550 Install New Service
    CAPEC-551 Modify Existing Service
    CAPEC-552 Install Rootkit
    CAPEC-556 Replace File Extension Handlers
    CAPEC-558 Replace Trusted Executable
    CAPEC-562 Modify Shared File
    CAPEC-563 Add Malicious File to Shared Webroot
    CAPEC-564 Run Software at Logon
    CAPEC-578 Disable Security Software
    CAPEC-62 Cross Site Request Forgery

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High