Vulnerability-Lookup

GHSA-C9GW-HVQQ-F33R

Vulnerability from github – Published: 2026-04-16 21:18 – Updated: 2026-04-16 21:18

Summary

Flowise: Authenticated RCE Via MCP Adapters

Details

Summary

Due to unsafe serialization of stdio commands in the MCP adapter, an authenticated attacker can add an MCP stdio server with an arbitrary command, achieving command execution.

Details

The vulnerability lies in a bug in the input sanitization from the “Custom MCP” configuration in http://localhost:3000/canvas - where any user can add a new MCP, when doing so - adding a new MCP using stdio, the user can add any command, even though your code have input sanitization checks such as validateCommandInjection and validateArgsForLocalFileAccess, and a list of predefined specific safe commands - these commands, for example "npx" can be combined with code execution arguments ("-c touch /tmp/pwn") that enable direct code execution on the underlying OS.

https://github.com/FlowiseAI/Flowise/blob/d848baeb6bd9737a1e7fc912349c45fbdcc7bb38/packages/components/nodes/tools/MCP/core.ts#L223

https://github.com/FlowiseAI/Flowise/blob/d848baeb6bd9737a1e7fc912349c45fbdcc7bb38/packages/components/nodes/tools/MCP/core.ts#L177

https://github.com/FlowiseAI/Flowise/blob/d848baeb6bd9737a1e7fc912349c45fbdcc7bb38/packages/components/nodes/tools/MCP/core.ts#L269

PoC

Create a new Custom MCP and add an "npx -c" command.

{
    "command": "npx",
    "args": [
        "-c",
        "touch /tmp/pwn"
    ]
}

Screenshot 2026-01-12 at 18 32 37

Impact

This is an authenticated arbitrary command execution due to unsanitized input, even though the input is sanitized, more protections should be added in order to close ways for attackers to execute arbitrary commands.

Severity ?

9.9 (Critical)


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

Show details on source website

JSON

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{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 3.0.13"
      },
      "package": {
        "ecosystem": "npm",
        "name": "flowise"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.1.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 3.0.13"
      },
      "package": {
        "ecosystem": "npm",
        "name": "flowise-components"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.1.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-40933"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-78"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-04-16T21:18:17Z",
    "nvd_published_at": null,
    "severity": "CRITICAL"
  },
  "details": "### Summary\nDue to unsafe serialization of stdio commands in the MCP adapter, an authenticated attacker can add an MCP stdio server with an arbitrary command, achieving command execution.\n\n### Details\nThe vulnerability lies in a bug in the input sanitization from the \u201cCustom MCP\u201d configuration in http://localhost:3000/canvas - where any user can add a new MCP, when doing so - adding a new MCP using stdio, the user can add any command, even though your code have input sanitization checks such as validateCommandInjection and validateArgsForLocalFileAccess, and a list of predefined specific safe commands - these commands, for example \"npx\" can be combined with code execution arguments (\"-c touch /tmp/pwn\") that enable direct code execution on the underlying OS.\n\nhttps://github.com/FlowiseAI/Flowise/blob/d848baeb6bd9737a1e7fc912349c45fbdcc7bb38/packages/components/nodes/tools/MCP/core.ts#L223\n\nhttps://github.com/FlowiseAI/Flowise/blob/d848baeb6bd9737a1e7fc912349c45fbdcc7bb38/packages/components/nodes/tools/MCP/core.ts#L177\n\nhttps://github.com/FlowiseAI/Flowise/blob/d848baeb6bd9737a1e7fc912349c45fbdcc7bb38/packages/components/nodes/tools/MCP/core.ts#L269\n\n\n### PoC\nCreate a new Custom MCP and add an \"npx -c\" command.\n```\n{\n    \"command\": \"npx\",\n    \"args\": [\n        \"-c\",\n        \"touch /tmp/pwn\"\n    ]\n}\n```\n\u003cimg width=\"358\" height=\"628\" alt=\"Screenshot 2026-01-12 at 18 32 37\" src=\"https://github.com/user-attachments/assets/d95c1ae2-23a7-4afe-b586-722003baf50e\" /\u003e\n\n### Impact\nThis is an authenticated arbitrary command execution due to unsanitized input, even though the input is sanitized, more protections should be added in order to close ways for attackers to execute arbitrary commands.",
  "id": "GHSA-c9gw-hvqq-f33r",
  "modified": "2026-04-16T21:18:17Z",
  "published": "2026-04-16T21:18:17Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/FlowiseAI/Flowise/security/advisories/GHSA-c9gw-hvqq-f33r"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/FlowiseAI/Flowise"
    },
    {
      "type": "WEB",
      "url": "https://www.ox.security/blog/mcp-supply-chain-advisory-rce-vulnerabilities-across-the-ai-ecosystem"
    },
    {
      "type": "WEB",
      "url": "https://www.ox.security/blog/the-mother-of-all-ai-supply-chains-critical-systemic-vulnerability-at-the-core-of-the-mcp"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Flowise: Authenticated RCE Via MCP Adapters"
}

CVE-2026-40933 (GCVE-0-2026-40933)

Vulnerability from cvelistv5 – Published: 2026-04-21 21:00 – Updated: 2026-04-22 13:20

Title

Flowise: Authenticated RCE Via MCP Adapters

Summary

Flowise is a drag & drop user interface to build a customized large language model flow. Prior to 3.1.0, due to unsafe serialization of stdio commands in the MCP adapter, an authenticated attacker can add an MCP stdio server with an arbitrary command, achieving command execution. The vulnerability lies in a bug in the input sanitization from the “Custom MCP” configuration in http://localhost:3000/canvas - where any user can add a new MCP, when doing so - adding a new MCP using stdio, the user can add any command, even though your code have input sanitization checks such as validateCommandInjection and validateArgsForLocalFileAccess, and a list of predefined specific safe commands - these commands, for example "npx" can be combined with code execution arguments ("-c touch /tmp/pwn") that enable direct code execution on the underlying OS. This vulnerability is fixed in 3.1.0.

Severity ?

10 (Critical)


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

CWE

CWE-78 - Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')

Assigner

GitHub_M

References

URL

Tags

	https://github.com/FlowiseAI/Flowise/security/adv…	x_refsource_CONFIRM
	https://www.ox.security/blog/mcp-supply-chain-adv…	x_refsource_MISC
	https://www.ox.security/blog/the-mother-of-all-ai…	x_refsource_MISC

Impacted products

Vendor

Product

Version

FlowiseAI

Flowise

Affected: < 3.1.0

FlowiseAI

flowise-components

Affected: < 3.1.0

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-40933",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-04-22T13:20:05.790341Z",
                "version": "2.0.3"
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              "type": "ssvc"
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        "providerMetadata": {
          "dateUpdated": "2026-04-22T13:20:11.714Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "references": [
          {
            "tags": [
              "exploit"
            ],
            "url": "https://github.com/FlowiseAI/Flowise/security/advisories/GHSA-c9gw-hvqq-f33r"
          }
        ],
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "Flowise",
          "vendor": "FlowiseAI",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 3.1.0"
            }
          ]
        },
        {
          "product": "flowise-components",
          "vendor": "FlowiseAI",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 3.1.0"
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        }
      ],
      "descriptions": [
        {
          "lang": "en",
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        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "HIGH",
            "baseScore": 10,
            "baseSeverity": "CRITICAL",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "HIGH",
            "privilegesRequired": "LOW",
            "scope": "CHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-78",
              "description": "CWE-78: Improper Neutralization of Special Elements used in an OS Command (\u0027OS Command Injection\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-04-21T21:00:35.747Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
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      "references": [
        {
          "name": "https://github.com/FlowiseAI/Flowise/security/advisories/GHSA-c9gw-hvqq-f33r",
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        },
        {
          "name": "https://www.ox.security/blog/mcp-supply-chain-advisory-rce-vulnerabilities-across-the-ai-ecosystem",
          "tags": [
            "x_refsource_MISC"
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          "url": "https://www.ox.security/blog/mcp-supply-chain-advisory-rce-vulnerabilities-across-the-ai-ecosystem"
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          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://www.ox.security/blog/the-mother-of-all-ai-supply-chains-critical-systemic-vulnerability-at-the-core-of-the-mcp"
        }
      ],
      "source": {
        "advisory": "GHSA-c9gw-hvqq-f33r",
        "discovery": "UNKNOWN"
      },
      "title": "Flowise: Authenticated RCE Via MCP Adapters"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
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    "datePublished": "2026-04-21T21:00:35.747Z",
    "dateReserved": "2026-04-15T20:40:15.518Z",
    "dateUpdated": "2026-04-22T13:20:11.714Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
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}

Sightings

Author	Source	Type	Date

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.

Action not permitted

GHSA-C9GW-HVQQ-F33R

Summary

Details

PoC

Impact

CVE-2026-40933 (GCVE-0-2026-40933)

Tags

Sightings

Nomenclature