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CVE PROGRAM SOURCE RECORD9.8 Critical

CVE-2026-90898

Bifrost unauthenticated remote code execution via MCP stdio client registration

Description

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.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

maximhq Bifrost

Default version status: unaffected

  • 0 to < 2.1.0affected

References