CVE-2026-90898: Bifrost registers MCP clients through its management API

Q: How do I fix CVE-2026-90898?

No fixed release is listed yet. Watch the vendor advisory and apply any mitigation shown on this page.

Q: Is CVE-2026-90898 being exploited?

CVE-2026-90898 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-90898 affect?

CVE-2026-90898 affects affected software. Severity is critical (CVSS 9.8). 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.

Q: How urgent is CVE-2026-90898?

Priority 63/100. Critical severity; CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action

This week

CRITICAL 9.8REMOTE

CVE-2026-90898 is a critical-severity flaw (CVSS 9.8) affecting affected software. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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

Why this priority

Critical severity
CISA SSVC: automatable with total technical impact
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	2.3% (top 17%)
CISA exploited list	No
Weakness	CWE-284, CWE-306
Published	2026-09-14
Last modified	2026-09-18

Publisher (CNA): JFrog

Last updated 2026-09-18 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Timeline

2026-09-14 11:17 UTCPublished CVE record published
2026-09-18 19:31 UTCUpdated Record last modified

Exact fixes by distribution

Fedora ELN · xfsdump · FIXED · 3.3.0-3.eln159 · FEDORA-2026-6e9bb3f901 · source

sudo dnf upgrade --advisory=FEDORA-2026-6e9bb3f901

Fedora 46 · fio · FIXED · 3.43-2.fc46 · FEDORA-2026-b36219886b · source

sudo dnf upgrade --advisory=FEDORA-2026-b36219886b

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

GitHub PoC: HORKimhab/CVE-2026-90898 (0 stars)
Nuclei scan template: Bifrost < 2.1.0 - Unauthenticated MCP Stdio Command Execution

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-90898?

No fixed release is listed yet. Watch the vendor advisory and apply any mitigation shown on this page.

Is CVE-2026-90898 being exploited?

CVE-2026-90898 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-90898 affect?

CVE-2026-90898 affects affected software. Severity is critical (CVSS 9.8). 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.

How urgent is CVE-2026-90898?

Priority 63/100. Critical severity; CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action

References

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