Resource exhaustion in multer - CVE-2026-5079
Published: June 15, 2026
Vulnerability identifier: #VU134533
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-5079
CWE-ID: CWE-400
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Express.js
Affected software:
multer
multer
Detailed vulnerability description
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to uncontrolled resource consumption in the append-field dependency used by multipart form data processing when parsing deeply nested field names in bracket notation. A remote attacker can send a specially crafted multipart request to cause a denial of service.
A single HTTP request is sufficient to trigger the issue.
How to mitigate CVE-2026-5079
Install security update from vendor's website.