What is CVE-2026-90898?

CVE-2026-90898 is a critical-severity vulnerability in Maximhq Bifrost, classified under Improper Access Control. CVSS score: 9.8/10. Published 2026-09-14.

How severe is CVE-2026-90898?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Auth bypass in Maximhq Bifrost

CVE-2026-90898

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 v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

Affected products

Maximhq Bifrost

Weakness classification (CWE)

References

reefs@jfrog.com (patch)
reefs@jfrog.com (patch)
reefs@jfrog.com (release-notes)
reefs@jfrog.com (product)

Frequently asked questions

What is CVE-2026-90898?: CVE-2026-90898 is a critical-severity vulnerability in Maximhq Bifrost, classified under Improper Access Control. CVSS score: 9.8/10. Published 2026-09-14.
How severe is CVE-2026-90898?: Critical severity. CVSS v3 base score is 9.8 out of 10.