CVE-2026-90898
Bifrost unauthenticated remote code execution via MCP stdio client registration
CRITICAL 9.8EPSS 2.3%
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
- maximhq · Bifrost
- CVSS v3.1 JFROG
- 9.8 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - EPSS
- 2.31% chance of exploitation in the next 30 days, 83rd percentile
- Nuclei
- critical · CWE-78
- Published
- 2026-09-14