Skip to content

Flowise Pre-auth Arbitrary File Upload

Critical
HenryHengZJ published GHSA-h42x-xx2q-6v6g Mar 13, 2025

Package

No package listed

Affected versions

<= 2.2.4

Patched versions

None

Description

Summary

An unauthorized attacker can leverage the whitelisted route /api/v1/attachments to upload arbitrary files when the storageType is set to local (default).

Details

When a new request arrives, the system first checks if the URL starts with /api/v1/. If it does, the system then verifies whether the URL is included in the whitelist (whitelistURLs). If the URL is whitelisted, the request proceeds; otherwise, the system enforces authentication.

@ /packages/server/src/index.ts

           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 case sensitive
                    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()
                        } else if (req.headers['x-request-from'] === 'internal') {
                            basicAuthMiddleware(req, res, next)
                        } else {
                            const isKeyValidated = await validateAPIKey(req)
                            if (!isKeyValidated) {
                                return res.status(401).json({ error: 'Unauthorized Access' })
                            }
                            next()
                        }
                    } else {
                        return res.status(401).json({ error: 'Unauthorized Access' })
                    }
                } else {
                    // If the req path does not contain /api/v1, then allow the request to pass through, example: /assets, /canvas
                    next()
                }
            }

The whitelist is defined as follows

export const WHITELIST_URLS = [
    '/api/v1/verify/apikey/',
    '/api/v1/chatflows/apikey/',
    '/api/v1/public-chatflows',
    '/api/v1/public-chatbotConfig',
    '/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'
]

This means that every route in the whitelist does not require authentication. Now, let's examine the /api/v1/attachments route.

@ /packages/server/src/routes/attachments/index.ts

const router = express.Router()
// CREATE
router.post('/:chatflowId/:chatId', getMulterStorage().array('files'), attachmentsController.createAttachment)
export default router

After several calls, the request reaches the createFileAttachment function @ (packages/server/src/utils/createAttachment.ts)
Initially, the function retrieves chatflowid and chatId from the request without any additional validation. The only check performed is whether these parameters exist in the request.

    const chatflowid = req.params.chatflowId
    if (!chatflowid) {
        throw new Error(
            'Params chatflowId is required! Please provide chatflowId and chatId in the URL: /api/v1/attachments/:chatflowId/:chatId'
        )
    }

    const chatId = req.params.chatId
    if (!chatId) {
        throw new Error(
            'Params chatId is required! Please provide chatflowId and chatId in the URL: /api/v1/attachments/:chatflowId/:chatId'
        )
    }

Next, the function retrieves the uploaded files and attempts to add them to the storage by calling the addArrayFilesToStorage function.

const files = (req.files as Express.Multer.File[]) || []
    const fileAttachments = []
    if (files.length) {
        // ...
        for (const file of files) {
            const fileBuffer = await getFileFromUpload(file.path ?? file.key)  // get the uploaded file
            const fileNames: string[] = []
            file.originalname = Buffer.from(file.originalname, 'latin1').toString('utf8')
            // add it to the storage
            const storagePath = await addArrayFilesToStorage(file.mimetype, 
                                                             fileBuffer,
                                                             file.originalname,
                                                             fileNames,
                                                             chatflowid, chatId) // add it to the storage

            // ...

            await removeSpecificFileFromUpload(file.path ?? file.key) // delete from tmp
           //  ...

                fileAttachments.push({
                    name: file.originalname,
                    mimeType: file.mimetype,
                    size: file.size,
                    content
                })
            } catch (error) {
                throw new Error(`Failed operation: createFileAttachment - ${getErrorMessage(error)}`)
            }
        }
    }

    return fileAttachments

Now lets take a look at addArrayFilesToStorage function @ (/packages/components/src/storageUtils.ts)

export const addArrayFilesToStorage = async (mime: string, bf: Buffer, fileName: string, fileNames: string[], ...paths: string[]) => {
    const storageType = getStorageType()

    const sanitizedFilename = _sanitizeFilename(fileName)
    if (storageType === 's3') {
      // ...
    } else {
        const dir = path.join(getStoragePath(), ...paths) // PATH TRAVERSAL.
        if (!fs.existsSync(dir)) {
            fs.mkdirSync(dir, { recursive: true })
        }
        const filePath = path.join(dir, sanitizedFilename)
        fs.writeFileSync(filePath, bf)
        fileNames.push(sanitizedFilename)
        return 'FILE-STORAGE::' + JSON.stringify(fileNames)
    }
}

As noted in the comment, to construct the directory, the function joins the output of the getStoragePath function with ...paths, which are essentially the chatflowid and chatId extracted earlier from the request.
However, as mentioned previously, these values are not validated to ensure they are UUIDs or numbers. As a result, an attacker could manipulate these variables to set the dir variable to any value.
Combined with the fact that the filename is also provided by the user, this leads to unauthenticated arbitrary file upload.

POC

This is the a HTTP request. As observed, we are not authenticated, and by manipulating the chatId parameter, we can perform a path traversal. In this example, we overwrite the api.json file, which contains the API keys for the system.

File Uplaod Vulnerability.

in this example, the dir variable will be

var dir = '/root/.flowise/storage/test/../../../../../../../../root/.flowise/'

and the file name is api.json

And the API Keys in the UI

File Uplaod Vulnerability.

Impact

This vulnerability could potentially lead to

  • Remote Code Execution
  • Server Takeover
  • Data Theft
    And more

Severity

Critical

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v4 base metrics

Exploitability Metrics
Attack Vector Network
Attack Complexity Low
Attack Requirements None
Privileges Required None
User interaction None
Vulnerable System Impact Metrics
Confidentiality High
Integrity High
Availability High
Subsequent System Impact Metrics
Confidentiality None
Integrity None
Availability None

CVSS v4 base metrics

Exploitability Metrics
Attack Vector: This metric reflects the context by which vulnerability exploitation is possible. This metric value (and consequently the resulting severity) will be larger the more remote (logically, and physically) an attacker can be in order to exploit the vulnerable system. The assumption is that the number of potential attackers for a vulnerability that could be exploited from across a network is larger than the number of potential attackers that could exploit a vulnerability requiring physical access to a device, and therefore warrants a greater severity.
Attack Complexity: This metric captures measurable actions that must be taken by the attacker to actively evade or circumvent existing built-in security-enhancing conditions in order to obtain a working exploit. These are conditions whose primary purpose is to increase security and/or increase exploit engineering complexity. A vulnerability exploitable without a target-specific variable has a lower complexity than a vulnerability that would require non-trivial customization. This metric is meant to capture security mechanisms utilized by the vulnerable system.
Attack Requirements: This metric captures the prerequisite deployment and execution conditions or variables of the vulnerable system that enable the attack. These differ from security-enhancing techniques/technologies (ref Attack Complexity) as the primary purpose of these conditions is not to explicitly mitigate attacks, but rather, emerge naturally as a consequence of the deployment and execution of the vulnerable system.
Privileges Required: This metric describes the level of privileges an attacker must possess prior to successfully exploiting the vulnerability. The method by which the attacker obtains privileged credentials prior to the attack (e.g., free trial accounts), is outside the scope of this metric. Generally, self-service provisioned accounts do not constitute a privilege requirement if the attacker can grant themselves privileges as part of the attack.
User interaction: This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable system. This metric determines whether the vulnerability can be exploited solely at the will of the attacker, or whether a separate user (or user-initiated process) must participate in some manner.
Vulnerable System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the VULNERABLE SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the VULNERABLE SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the VULNERABLE SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
Subsequent System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the SUBSEQUENT SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the SUBSEQUENT SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the SUBSEQUENT SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

CVE ID

No known CVE

Weaknesses

Credits