expressjs multer up to 2.2.0 Disk Storage Engine denial of service

Summaryinfo

A vulnerability was found in expressjs multer up to 2.2.0 and classified as problematic. Affected by this vulnerability is an unknown functionality of the component Disk Storage Engine. Executing a manipulation can lead to denial of service. This vulnerability is handled as CVE-2026-77037. The attack can be executed remotely. There is not any exploit available.

Detailsinfo

A vulnerability classified as problematic was found in expressjs multer up to 2.2.0. This vulnerability affects an unknown code of the component Disk Storage Engine. The manipulation with an unknown input leads to a denial of service vulnerability. The CWE definition for the vulnerability is CWE-404. The product does not release or incorrectly releases a resource before it is made available for re-use. As an impact it is known to affect availability. CVE summarizes:

multer is a middleware for handling multipart/form-data in Node.js. In version 2.2.0, when a disk-backed upload is aborted or truncated before the write stream finishes, multer's disk storage engine removes the visible file but does not close the underlying write file descriptor, leaving a deleted but still open descriptor. A remote attacker able to reach an upload route using the built-in disk storage can send repeated aborted or malformed multipart uploads, each one leaking a file descriptor and retaining disk blocks until the process exits, which can exhaust resources and cause a denial of service. The issue is fixed in multer 2.3.0, which closes the destination write stream on abnormal source termination and defers cleanup until the stream has closed. Upgrade to multer 2.3.0 to remediate.

The advisory is available at github.com. This vulnerability was named CVE-2026-77037 since 08/20/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. The technical details are unknown and an exploit is not available. This vulnerability is assigned to T1499 by the MITRE ATT&CK project.

Upgrading to version 2.3.0 eliminates this vulnerability.

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Productinfo

Vendor

• expressjs

Name

• multer

Version

• 2.0
• 2.1
• 2.2.0

Website

• Product: https://github.com/expressjs/multer/

CPE 2.3info

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CPE 2.2info

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