GHSA-q7qp-rjg7-q26m

ghsaUSosv

multer vulnerable to Denial of Service via a pending asynchronous fileFilter after request teardown

view advisory published 2026-10-23Licence: CC-BY-4.0

### Impact When `multer` is configured with an asynchronous `fileFilter`, a single request can crash the Node.js process. If a request is aborted (for example when one file is rejected) while another file's async `fileFilter` is still pending, the pending callback later resumes a parsing stream that multer has already torn down. busboy then emits an error on a stream that no longer has an error listener, which Node raises as an unhandled `'error'` event, and the process exits. A single unauthenticated request is enough, so any application using `multer` with an asynchronous `fileFilter` is affected, regardless of storage engine. Uploads using a synchronous `fileFilter` are not affected. ### Patches Users should upgrade to `multer` `2.5.0` or later. ### Workarounds Use a synchronous `fileFilter`.

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describes (1)

Related CVEs.

IDseverity exploitable
CVE-2026-113872US—Exploit
multer is a middleware for Node.js that handles multipart/form-data file uploads. In versions from 2.0.0 before 2.5.0, when multer is configured with an asynchronous fileFilter, a…
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