CVE-2026-90898
Bifrost unauthenticated remote code execution via MCP stdio client registration
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.
INFO
Published Date :
Sept. 14, 2026, 10:18 a.m.
Last Modified :
Sept. 14, 2026, 10:18 a.m.
Remotely Exploit :
Yes !
Source :
JFROG
Affected Products
The following products are affected by CVE-2026-90898
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | CRITICAL | 48a46f29-ae42-4e1d-90dd-c1676c1e5e6d |
Solution
- Enable governance.auth_config.is_enabled in Bifrost.
- Apply version v2.1.0 or later of transports.
- Restart the Bifrost service.
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CVE-2026-90898 vulnerability anywhere in the article.