| Package | Affected versions | Patched versions |
|---|---|---|
| flowise | < 3.0.13 | 3.0.13 |
| flowise | < 3.0.13 | 3.0.13 |
Vulnerability Overview
/api/v1/attachments/:chatflowId/:chatId endpoint is listed in WHITELIST_URLS, allowing unauthenticated access to the file upload API.chatbotConfig.fullFileUpload.allowedUploadFileTypes, it implicitly trusts the client-provided Content-Type header (file.mimetype) without verifying the file's actual content (magic bytes) or extension (file.originalname).Content-Type as a permitted type (e.g., application/pdf) while uploading malicious scripts or arbitrary files. Once uploaded via addArrayFilesToStorage, these files persist in backend storage (S3, GCS, or local disk). This vulnerability serves as a critical entry point that, when chained with other features like static hosting or file retrieval, can lead to Stored XSS, malicious file hosting, or Remote Code Execution (RCE).Vulnerable Code
Upload Route Definition
// CREATE
router.post('/:chatflowId/:chatId', getMulterStorage().array('files'), attachmentsController.createAttachment)
export default router
Mount /api/v1/attachments to the global router
const router = express.Router()
router.use('/ping', pingRouter)
router.use('/apikey', apikeyRouter)
router.use('/assistants', assistantsRouter)
router.use('/attachments', attachmentsRouter)
Include /api/v1/attachments in the WHITELIST_URLS list
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Scan my site freeexport const WHITELIST_URLS = [
'/api/v1/verify/apikey/',
'/api/v1/chatflows/apikey/',
'/api/v1/public-chatflows',
'/api/v1/public-chatbotConfig',
'/api/v1/public-executions',
'/api/v1/prediction/',
'/api/v1/vector/upsert/',
'/api/v1/node-icon/',
'/api/v1/components-credentials-icon/',
'/api/v1/chatflows-streaming',
'/api/v1/chatflows-uploads',
'/api/v1/openai-assistants-file/download',
'/api/v1/feedback',
'/api/v1/leads',
'/api/v1/get-upload-file',
'/api/v1/ip',
'/api/v1/ping',
'/api/v1/version',
'/api/v1/attachments',
'/api/v1/metrics',
Bypass JWT validation if the URL is whitelisted
const denylistURLs = process.env.DENYLIST_URLS ? process.env.DENYLIST_URLS.split(',') : []
const whitelistURLs = WHITELIST_URLS.filter((url) => !denylistURLs.includes(url))
const URL_CASE_INSENSITIVE_REGEX: RegExp = /\/api\/v1\//i
const URL_CASE_SENSITIVE_REGEX: RegExp = /\/api\/v1\//
await initializeJwtCookieMiddleware(this.app, this.identityManager)
this.app.use(async (req, res, next) => {
// Step 1: Check if the req path contains /api/v1 regardless of case
if (URL_CASE_INSENSITIVE_REGEX.test(req.path)) {
// Step 2: Check if the req path is casesensitive
if (URL_CASE_SENSITIVE_REGEX.test(req.path)) {
// Step 3: Check if the req path is in the whitelist
const isWhitelisted = whitelistURLs.some((url) => req.path.startsWith(url))
if (isWhitelisted) {
next()
Multer Configuration: Saves files without file type validation
export const getUploadPath = (): string => {
return process.env.BLOB_STORAGE_PATH
? path.join(process.env.BLOB_STORAGE_PATH, 'uploads')
: path.join(getUserHome(), '.flowise', 'uploads')
}
export function generateId() {
return uuidv4()
}
export const getMulterStorage = () => {
const storageType = process.env.STORAGE_TYPE ? process.env.STORAGE_TYPE : 'local'
if (storageType === 's3') {
const s3Client = getS3Config().s3Client
const Bucket = getS3Config().Bucket
const upload = multer({
storage: multerS3({
s3: s3Client,
bucket: Bucket,
metadata: function (req, file, cb) {
cb(null, { fieldName: file.fieldname, originalName: file.originalname })
},
key: function (req, file, cb) {
cb(null, `${generateId()}`)
}
})
})
return upload
} else if (storageType === 'gcs') {
return multer({
storage: new MulterGoogleCloudStorage({
projectId: process.env.GOOGLE_CLOUD_STORAGE_PROJ_ID,
bucket: process.env.GOOGLE_CLOUD_STORAGE_BUCKET_NAME,
keyFilename: process.env.GOOGLE_CLOUD_STORAGE_CREDENTIAL,
uniformBucketLevelAccess: Boolean(process.env.GOOGLE_CLOUD_UNIFORM_BUCKET_ACCESS) ?? true,
destination: `uploads/${generateId()}`
})
})
} else {
return multer({ dest: getUploadPath() })
}
}
Transfers uploaded files to storage without verification
const files = (req.files as Express.Multer.File[]) || []
const fileAttachments = []
if (files.length) {
const isBase64 = req.body.base64
for (const file of files) {
if (!allowedFileTypes.length) {
throw new InternalFlowiseError(
StatusCodes.BAD_REQUEST,
`File type '${file.mimetype}' is not allowed. Allowed types: ${allowedFileTypes.join(', ')}`
)
}
// Validate file type against allowed types
if (allowedFileTypes.length > 0 && !allowedFileTypes.includes(file.mimetype)) {
throw new InternalFlowiseError(
StatusCodes.BAD_REQUEST,
`File type '${file.mimetype}' is not allowed. Allowed types: ${allowedFileTypes.join(', ')}`
)
}
await checkStorage(orgId, subscriptionId, appServer.usageCacheManager)
const fileBuffer = await getFileFromUpload(file.path ?? file.key)
const fileNames: string[] = []
// Address file name with special characters: https://github.com/expressjs/multer/issues/1104
file.originalname = Buffer.from(file.originalname, 'latin1').toString('utf8')
const { path: storagePath, totalSize } = await addArrayFilesToStorage(
file.mimetype,
fileBuffer,
file.originalname,
fileNames,
orgId,
chatflowid,
chatId
)
PoC Description
shell.js containing arbitrary JavaScript code (or a malicious payload).multipart/form-data request to the /api/v1/attachments/891f64a2-a26f-4169-b333-905dc96c200a/:chatId endpoint without any authentication (login, session, or API keys).shell.js but spoof the Content-Type header as application/pdf.file.mimetype, forcing it to process the malicious JS file as an allowed PDF, thereby confirming unauthenticated arbitrary file upload.PoC
curl -X POST \
"http://localhost:3000/api/v1/attachments/891f64a2-a26f-4169-b333-905dc96c200a/$(uuidgen)" \
-F "[email protected];type=application/pdf"
1. Root Cause
The vulnerability stems from relying solely on the MIME type without cross-validating the file extension or actual content. This allows attackers to upload executable files (e.g., .js, .php) or malicious scripts (.html) by masquerading them as benign images or documents.
2. Key Attack Scenarios
3. Impact This vulnerability is rated as High severity. The risk is particularly critical if the system utilizes shared storage (e.g., S3, GCS) or static hosting features, as the compromise could spread to the entire infrastructure and affect other tenants.