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Multer vulnerable to Denial of Service via incomplete cleanup of aborted uploads

Moderate severity GitHub Reviewed Published Jun 15, 2026 in expressjs/multer • Updated Jun 17, 2026

Package

npm multer (npm)

Affected versions

>= 2.0.0-alpha.1, < 2.2.0
>= 3.0.0-alpha.1, < 3.0.0-alpha.2

Patched versions

2.2.0
3.0.0-alpha.2

Description

Impact

A vulnerability in Multer allows an attacker to trigger a Denial of Service (DoS) by aborting or sending malformed multipart uploads, causing orphaned partial files to accumulate on disk when using diskStorage.

Patches

Users should upgrade to 2.2.0, 3.0.0-alpha.2 or higher

Workarounds

None

References

@UlisesGascon UlisesGascon published to expressjs/multer Jun 15, 2026
Published by the National Vulnerability Database Jun 15, 2026
Published to the GitHub Advisory Database Jun 17, 2026
Reviewed Jun 17, 2026
Last updated Jun 17, 2026

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

EPSS score

Weaknesses

Incomplete Cleanup

The product does not properly clean up and remove temporary or supporting resources after they have been used. Learn more on MITRE.

CVE ID

CVE-2026-5038

GHSA ID

GHSA-3p4h-7m6x-2hcm

Source code

Credits

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