7.5 High

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

CVE-2026-113872

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.

Proof-of-concept code is published

Public PoC

Public PoCsantihabib/multer-CVE-2026-113872

Signals come from Exploit-DB, Metasploit, Nuclei and published proof-of-concept repositories. Their absence means nothing was found, not that nothing exists.

Assessment

CVSS: 7.5 (v3.1)
Severity: High
EPSS: 0.00442% chance of exploitation in the next 30 days
Known exploited: Not listed in CISA KEV
Exploit availability: Public PoC
Published: 23 October 2026
Last updated: 23 October 2026
Affected: npm · multer
Weakness: CWE-248, CWE-404

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

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