What’s Vulnerable › Vulnerabilities

CVE-2026-88932: multer vulnerable to Denial of Service via orphaned disk writes on aborted uploads

• Severity: medium (CVSS 5.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-14 · updated 2026-09-16
• Weakness: CWE-400

Description

multer is a Node.js middleware for handling multipart/form-data uploads. In versions 2.2.0 through 2.3.0, when a request using disk storage is aborted mid-upload, file writes that complete after multer has already run its abort cleanup are not removed, so each aborted upload can leave an orphaned file on disk. A remote unauthenticated attacker can repeatedly start and abort uploads to accumulate orphaned files and exhaust disk space, causing a denial of service. The issue is fixed in multer 2.4.0, and users should upgrade to 2.4.0 or later.

Affected products

• multer: from 2.2.0 before 2.4.0 — fixed in 2.4.0

How to fix

Upgrade to a fixed version: multer 2.4.0. Check the vendor advisory for mitigations.

References

• https://cna.openjsf.org/security-advisories.html
• https://github.com/expressjs/multer/security/advisories/GHSA-3pph-fpjx-jg34

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