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

### 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`.

Source published

23 Oct 2026 22:08:22 UTC

Source modified

23 Oct 2026 22:15:04 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Publisher rating · HIGH