# CVE-2026-90898

## Summary

- **CVE ID:** CVE-2026-90898
- **Severity:** CRITICAL
- **CVSS Score:** 9.8 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H)
- **CWE:** CWE-306, CWE-284
- **Published:** Sep 14, 2026
- **Last Modified:** Sep 14, 2026

## 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

- maximhq — Bifrost (0)

## References

- [CNA](https://github.com/maximhq/bifrost/pull/6757)
- [CNA](https://github.com/maximhq/bifrost/commit/12e170352bd25eab1ae9ba16611f1797d1fd8fdc)
- [CNA](https://github.com/maximhq/bifrost/releases/tag/transports/v2.1.0)
- [CNA](https://github.com/maximhq/bifrost)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.34%
- **EPSS Percentile:** 27.8

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-18._