Vulnerability-Lookup

CVE-2026-90898 (GCVE-0-2026-90898)

Vulnerability from cvelistv5 – Published: 2026-09-14 10:18 – Updated: 2026-09-14 11:19

Title

Bifrost unauthenticated remote code execution via MCP stdio client registration

Summary

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.

Severity

9.8 (Critical)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

SSVC

Exploitation: none Automatable: yes Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-14 11:01 UTC

CWE

CWE-306 - Missing Authentication for Critical Function
CWE-284 - Improper Access Control

Assigner

JFROG mitre root

References

4 references

URL	Tags
https://github.com/maximhq/bifrost/pull/6757	patch
https://github.com/maximhq/bifrost/commit/12e1703…	patch
https://github.com/maximhq/bifrost/releases/tag/t…	release-notes
https://github.com/maximhq/bifrost	product

Impacted products

1 product

Vendor	Product	Version	CPE status
maximhq	Bifrost	Affected: 0 , < 2.1.0 (semver)	guessed

Credits

Yuval Moravchick | JFrog

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-90898

Vulnerability from fkie_nvd - Published: 2026-09-14 11:17 - Updated: 2026-09-14 12:17

Severity

9.8 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Summary

References

	URL	Tags
	reefs@jfrog.com	https://github.com/maximhq/bifrost
	reefs@jfrog.com	https://github.com/maximhq/bifrost/commit/12e170352bd25eab1ae9ba16611f1797d1fd8fdc
	reefs@jfrog.com	https://github.com/maximhq/bifrost/pull/6757
	reefs@jfrog.com	https://github.com/maximhq/bifrost/releases/tag/transports/v2.1.0

Impacted products

	Vendor	Product	Version

JSON

To clipboard

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            {
              "lessThan": "2.1.0",
              "status": "affected",
              "version": "0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "source": "reefs@jfrog.com"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "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.\n\n\n\nThe 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).\n\n\n\n\u00a0transports/v2.1.0 refuses an unauthenticated stdio registration with 403. transports/v2.0.0 still allows it."
    }
  ],
  "id": "CVE-2026-90898",
  "lastModified": "2026-09-14T12:17:51.657",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 9.8,
          "baseSeverity": "CRITICAL",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 5.9,
        "source": "reefs@jfrog.com",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-90898",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-09-14T11:01:44.207374Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-09-14T11:17:08.237",
  "references": [
    {
      "source": "reefs@jfrog.com",
      "url": "https://github.com/maximhq/bifrost"
    },
    {
      "source": "reefs@jfrog.com",
      "url": "https://github.com/maximhq/bifrost/commit/12e170352bd25eab1ae9ba16611f1797d1fd8fdc"
    },
    {
      "source": "reefs@jfrog.com",
      "url": "https://github.com/maximhq/bifrost/pull/6757"
    },
    {
      "source": "reefs@jfrog.com",
      "url": "https://github.com/maximhq/bifrost/releases/tag/transports/v2.1.0"
    }
  ],
  "sourceIdentifier": "reefs@jfrog.com",
  "vulnStatus": "Received",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-284"
        },
        {
          "lang": "en",
          "value": "CWE-306"
        }
      ],
      "source": "reefs@jfrog.com",
      "type": "Secondary"
    }
  ]
}

GHSA-GQJQ-CGXR-8C7C

Vulnerability from github – Published: 2026-09-14 12:31 – Updated: 2026-09-14 12:31

Details

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.

Severity

9.8 (Critical)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Show details on source website

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{
  "affected": [],
  "aliases": [
    "CVE-2026-90898"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-284"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-14T11:17:08Z",
    "severity": "CRITICAL"
  },
  "details": "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.\n\n\n\nThe 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).\n\n\n\n\u00a0transports/v2.1.0 refuses an unauthenticated stdio registration with 403. transports/v2.0.0 still allows it.",
  "id": "GHSA-gqjq-cgxr-8c7c",
  "modified": "2026-09-14T12:31:40Z",
  "published": "2026-09-14T12:31:40Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-90898"
    },
    {
      "type": "WEB",
      "url": "https://github.com/maximhq/bifrost/pull/6757"
    },
    {
      "type": "WEB",
      "url": "https://github.com/maximhq/bifrost/commit/12e170352bd25eab1ae9ba16611f1797d1fd8fdc"
    },
    {
      "type": "WEB",
      "url": "https://github.com/maximhq/bifrost"
    },
    {
      "type": "WEB",
      "url": "https://github.com/maximhq/bifrost/releases/tag/transports/v2.1.0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.

Action not permitted

CVE-2026-90898 (GCVE-0-2026-90898)

FKIE_CVE-2026-90898

GHSA-GQJQ-CGXR-8C7C

Tags

Sightings

Nomenclature