Critical 9.8Published Sep 14, 2026

CVE-2026-90898Bifrost unauthenticated remote code execution via MCP stdio client registration

Updated under an hour ago (2026-10-19 10:10 UTC)

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It affects maximhq Bifrost. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Every CVE for maximhq Bifrost

Exploited in the last 30 days

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.

CVSS: 9.8 CRITICAL (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness (CWE): CWE-306, CWE-284
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: JFROG
NVD analysis: Awaiting Analysis
Record last updated: Sep 14, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

maximhq Bifrost maximhq:bifrost (from the name)	before 2.1.0	CNA record

References

https://github.com/maximhq/bifrost/pull/6757patch
https://github.com/maximhq/bifrost/commit/12e170352bd25eab1ae9ba16611f1797d1fd8fdcpatch
https://github.com/maximhq/bifrost/releases/tag/transports/v2.1.0release-notes
https://github.com/maximhq/bifrostproduct

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.