# CVE-2021-23597: Denial of Service (DoS)

> An attacker can crash the application by sending a multipart request with a specific property name, affecting users of the fastify-multipart library.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:P`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 11 Feb 2022
- **Updated:** 16 Sep 2024
- **Also known as:** GHSA-qh73-qc3p-rjv2, SNYK-JS-FASTIFYMULTIPART-2395480

## What is CVE-2021-23597?

CVE-2021-23597 is a high-severity denial of service vulnerability in fastify-multipart, published on 11 Feb 2022. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

This affects the package fastify-multipart before 5.3.1. By providing a name=constructor property it is still possible to crash the application. **Note:** This is a bypass of CVE-2020-8136 (https://security.snyk.io/vuln/SNYK-JS-FASTIFYMULTIPART-1290382).

Weakness: CWE-1321 (Improperly Controlled Modification of Object Prototype Attributes)

## Which versions are affected by CVE-2021-23597?

2 open source packages ship an affected version, including fastify-multipart. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `fastify-multipart` | npm | All versions | 5.3.1 |
| `fastify-multipart` | npm | All versions | 5.3.1 |

Products: Fastify Fastify-Multipart.

## How do I fix CVE-2021-23597?

Upgrade fastify-multipart to 5.3.1 or later.

## Is CVE-2021-23597 being exploited?

There is no known exploitation of CVE-2021-23597 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-2026-19474](https://insights.sbomify.com/CVE-2026-19474/): @fastify/multipart vulnerable to Denial of Service via temporary file leak on aborted upload (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-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-2021-23597 and fix it if it is affected.

What it is: CVE-2021-23597 is a high-severity denial of service vulnerability in fastify-multipart, published on 11 Feb 2022. 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-2021-23597 in the wild and no public exploit code.

Affected packages and fixed versions:
- fastify-multipart (npm): affected all versions; fixed in 5.3.1
- fastify-multipart (npm): affected all versions; fixed in 5.3.1

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-2021-23597/ (Markdown: https://insights.sbomify.com/CVE-2021-23597/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-23597
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-23597
- OSV: https://osv.dev/vulnerability/CVE-2021-23597

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-23597/
Summaries are generated and may contain mistakes; the official description above is the record.