@fastify/multipart is the multipart form-data and file upload plugin for the Fastify web framework. In versions 5.3.0 through 10.1.6, the plugin does not propagate a parser error to the file stream when a request body ends inside a file part with no closing boundary, even though the Content-Length is complete, the client does not abort, and no file size limit is exceeded. The plugin destroys the in-progress file stream without an error, so a handler that iterates the request parts and performs asynchronous work before consuming the file attaches to a stream that never emits an error or end event, and the request never responds while the connection stays open. An unauthenticated remote client can repeat these malformed uploads against such a route to accumulate pending connections and exhaust server resources, so the impact is availability only and exploitation depends on the application using a delayed file consumer. The issue is fixed in @fastify/multipart 10.1.7, where the parser error is propagated to the file stream so a delayed consumer settles with an error instead of hanging, and users should upgrade to 10.1.7 or later. There is no workaround other than upgrading.
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Mon, 02 Nov 2026 10:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | @fastify/multipart is the multipart form-data and file upload plugin for the Fastify web framework. In versions 5.3.0 through 10.1.6, the plugin does not propagate a parser error to the file stream when a request body ends inside a file part with no closing boundary, even though the Content-Length is complete, the client does not abort, and no file size limit is exceeded. The plugin destroys the in-progress file stream without an error, so a handler that iterates the request parts and performs asynchronous work before consuming the file attaches to a stream that never emits an error or end event, and the request never responds while the connection stays open. An unauthenticated remote client can repeat these malformed uploads against such a route to accumulate pending connections and exhaust server resources, so the impact is availability only and exploitation depends on the application using a delayed file consumer. The issue is fixed in @fastify/multipart 10.1.7, where the parser error is propagated to the file stream so a delayed consumer settles with an error instead of hanging, and users should upgrade to 10.1.7 or later. There is no workaround other than upgrading. | |
| Title | @fastify/multipart vulnerable to Denial of Service via a malformed upload hanging delayed file consumers | |
| Weaknesses | CWE-400 | |
| References |
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| Metrics |
cvssV3_1
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Status: PUBLISHED
Assigner: openjs
Published:
Updated: 2026-11-02T10:32:38.867Z
Reserved: 2026-10-27T10:32:52.571Z
Link: CVE-2026-117531
No data.
Status : Received
Published: 2026-11-02T11:17:30.853
Modified: 2026-11-02T11:17:30.853
Link: CVE-2026-117531
No data.
OpenCVE Enrichment
Updated: 2026-11-02T11:30:14Z
Weaknesses