CVE-2026-90898 — Bifrost unauthenticated remote code execution via MCP stdio client registration
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 MC…
Published: 2026-09-14 · CVSS: 9.8 · CVSS 3.1
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.
Source: CVE Program · Revision 8b16575c39f1e1810c5e863010da073d2d3285e7