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CVE

CVE-2026-90898

Bifrost unauthenticated remote code execution via MCP stdio client registration
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CVE

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 MCP handshake required.

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The default is governance.authconfig.isenabled=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).

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 transports/v2.1.0 refuses an unauthenticated stdio registration with 403. transports/v2.0.0 still allows it.

Package Versions Affected

Package Version
patch Availability
No items found.

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CVSS Version

Severity
Base Score
CVSS Version
Score Vector
C
H
U
9.8
-
3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
C
H
U
0
-
3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
C
H
U
9.8
-
3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Related Resources

No items found.

References

https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/90xxx/CVE-2026-90898.json, https://github.com/maximhq/bifrost/releases/tag/transports/v2.1.0, https://nvd.nist.gov/vuln/detail/CVE-2026-90898, https://github.com/maximhq/bifrost/commit/12e170352bd25eab1ae9ba16611f1797d1fd8fdc, https://github.com/maximhq/bifrost/pull/6757, git://github.com/maximhq/bifrost, https://github.com/maximhq/bifrost

Severity

9.8

CVSS Score
0
10

Basic Information

Base CVSS
9.8
EPSS Probability
0.00621%
EPSS Percentile
0.48146%
Introduced Version
0,v1.3.27,v1.2.13-0.20250914173734-1970e664c532,v0.0.0-20250914172548-cb343990a0dc,v1.1.9-0.20250708165040-7b8a7cdeeb02,v0.0.0-20250708154807-c287e90bdc4c
Fix Available
b211fdaed3b6829e126edaeb6b43503849c062a0,v2.1.0,v1.6.12-0.20260902151428-12e170352bd2

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