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Vulnerabilities

Vulnerability · CVE-2026-90898

Improper Access Control

Published Sep 14, 2026 · catalog updated Oct 23, 2026 · Bifrost

Patch now

CVE-2026-90898 is in the CISA known-exploited catalog. Confirm Bifrost against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Gaps on this record

  • No version range is stored. A customer cannot check an installed version against this record.
Severity
Critical9.8
Known exploitation
CISA KEV and VulnCheck KEV
EPSS
2.31%
Remediation
Remediation guidance
Affected products
vendor maximhq Bifrost

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. VulnCheck canary evidence.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • vendor maximhq Bifrostversion unspecified

How to fix CVE-2026-90898

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

CVE-2026-90898 is in the CISA known-exploited catalog. Confirm Bifrost against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Which versions are affected?

Affected version ranges are not on this record. Apply remediations or mitigations per vendor instructions or discontinue use of the product if remediation or mitigations are unavailable.

What should an analyst verify?

CWE-284: Improper Access Control; CWE-306: Missing Authentication for Critical Function. EPSS 2.31%. The CISA KEV listing is the exploitation evidence. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 17, 2026 · Nuclei Templates

    Detected

    CVE-2026-90898 has a public Nuclei detection template.

  2. Oct 23, 2026 · CISA KEV

    Known exploited

    Apply remediations or mitigations per vendor instructions or discontinue use of the product if remediation or mitigations are unavailable.

Sources

  • CVE.orgVulnerability recordCVE-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 call

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-90898

    30-day exploitation probability 2.31%

    first.org
  • Nuclei TemplatesDetection templateCVE-2026-90898

    CVE-2026-90898 has a public Nuclei detection template.

    github.com
  • VulnCheck KEVConfirmed exploitationCVE-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 call

    vulncheck.com

References

Freshness

Last verified in this catalog Oct 23, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.