# CVE-2026-19474: @fastify/multipart vulnerable to Denial of Service via temporary file leak on aborted upload

> An unauthenticated attacker can cause persistent disk consumption and denial of service by aborting multipart uploads, requiring an upgrade to the library.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 15 Aug 2026
- **Updated:** 17 Aug 2026
- **Also known as:** GHSA-62qx-hpj5-j6hc

## What is CVE-2026-19474?

CVE-2026-19474 is a high-severity denial of service vulnerability in @fastify/multipart, published on 15 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

@fastify/multipart is a multipart form-data parser for Fastify. In versions from 3.0.0 up to but not including 10.1.1, request.saveRequestFiles() can leave completed temporary files on disk when a client disconnects while the parser is advancing between multipart parts. The iterator rejection that occurs between parts falls outside the per-file cleanup path, so an earlier completed file is never removed. An unauthenticated client can repeat this to cause persistent, linear disk consumption, leading to denial of service. This is an incomplete-fix variant of CVE-2025-24033. The issue is fixed in @fastify/multipart 10.1.1. Users should upgrade to 10.1.1.

Weakness: CWE-770 (Allocation of Resources Without Limits or Throttling), CWE-459 (Incomplete Cleanup)

## Which versions are affected by CVE-2026-19474?

It affects 1 product.


Products: Fastify Fastify-Multipart.

## How do I fix CVE-2026-19474?

No fix has been published for CVE-2026-19474 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-19474 being exploited?

There is no known exploitation of CVE-2026-19474 in the wild and no public exploit code.

## Other vulnerabilities in @fastify/multipart

- [CVE-2026-18549](https://insights.sbomify.com/CVE-2026-18549/): @fastify/multipart vulnerable to Denial of Service via aborted upload after fileSize limit (high 7.5)
- [CVE-2023-25576](https://insights.sbomify.com/CVE-2023-25576/): @fastify/multipart vulnerable to DoS due to unlimited number of parts (high 7.5)
- [CVE-2021-23597](https://insights.sbomify.com/CVE-2021-23597/): Denial of Service (DoS) (high 7.5)
- [CVE-2020-8136](https://insights.sbomify.com/CVE-2020-8136/): Uncontrolled Resource Consumption in fastify-multipart (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-19474 and fix it if it is affected.

What it is: CVE-2026-19474 is a high-severity denial of service vulnerability in @fastify/multipart, published on 15 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-19474 in the wild and no public exploit code.

Affected product: @fastify/multipart. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-19474/ (Markdown: https://insights.sbomify.com/CVE-2026-19474/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-19474
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-19474
- OSV: https://osv.dev/vulnerability/CVE-2026-19474

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-19474/
Summaries are generated and may contain mistakes; the official description above is the record.