Multer vulnerable to Denial of Service from maliciously crafted requests

published 2025-05-19 17 mo ago modified 2026-09-10 1 mo ago also EUVD-2025-15796 , GHSA-4pg4-qvpc-4q3h

cvss: 7.5; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.8%; EPSS 0.8% chance of exploitation in 30 days, percentile 57%
public exploits: 0; none known

Multer is a node.js middleware for handling `multipart/form-data`. A vulnerability that is present starting in version 1.4.4-lts.1 and prior to version 2.0.0 allows an attacker to trigger a Denial of Service (DoS) by sending a malformed multi-part upload request. This request causes an unhandled exception, leading to a crash of the process. Users should upgrade to version 2.0.0 to receive a patch. No known workarounds are available.

Patch / fix

fixed in 2 links 1

npm multer 2.0.0
expressjs multer 2.0.0

github.com/expressjs/multer@2c8505f commit

CISA SSVC

Exploitation: none
Automatable: yes
Technical impact: partial
Assessed: 17 mo ago (2025-05-20)

Exploit prediction

0.81% chance of exploitation in the next 30 days, higher than 57% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	7.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
GitHub	3.1	7.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem	package	affected	fixed in
npm	multer	>=1.4.4-lts.1, <2.0.0	2.0.0

Affected products

expressjs multer

Classification

Weakness

CWE-248 Uncaught Exception

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.

Summary