@fastify/multipart vulnerable to Denial of Service via aborted upload after fileSize limit

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-18549
StatePUBLISHED
Assigneropenjs
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-15 14:17:07 UTC
Updated2026-09-02 15:13:16 UTC
Description@fastify/multipart is a multipart form-data parser for Fastify. In versions from 5.3.0 up to but not including 10.1.1, when the busboy fileSize limit truncates a file part, the plugin clears its internal current-file reference while the underlying stream is still open. If the client then aborts the connection before sending the terminating boundary, the abort cleanup finds no stream to destroy, so saveRequestFiles() never settles, the request handler hangs, and the temporary file already written to disk is never cleaned up. An unauthenticated client can repeat this to permanently leak temporary files and suspended handler executions, leading to disk and event-loop exhaustion. The issue is fixed in @fastify/multipart 10.1.1. Users should upgrade to 10.1.1.

Risk And Classification

Primary CVSS: v3.1 7.5 HIGH from ce714d77-add3-4f53-aff5-83d477b104bb

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS: 0.003400000 probability, percentile 0.268270000 (date 2026-09-02)

Problem Types: CWE-400 | CWE-664 | CWE-400 CWE-400: Uncontrolled Resource Consumption | CWE-664 CWE-664: Improper Control of a Resource Through its Lifetime

VersionSourceTypeScoreSeverityVector
3.1ce714d77-add3-4f53-aff5-83d477b104bbSecondary7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.1CNACVSS7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Fastify Fastify-multipart All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA @fastifymultipart @fastify/multipart affected 5.3.0 10.1.1 semver Not specified
CNA @fastifymultipart @fastify/multipart unaffected 10.1.1 semver Not specified

References

ReferenceSourceLinkTags
cna.openjsf.org/security-advisories.html ce714d77-add3-4f53-aff5-83d477b104bb cna.openjsf.org Third Party Advisory
github.com/fastify/fastify-multipart/security/advisories/GHSA-vmph-573x-... ce714d77-add3-4f53-aff5-83d477b104bb github.com Mitigation, Vendor Advisory
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: iaohkut-from-NightWolf-Team (en)

CNA: UlisesGascon (en)

CNA: mcollina (en)

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