CVE-2026-19474: @fastify/multipart is a multipart form-data parser for Fastify

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HIGH 7.5REMOTEUPGRADE

CVE-2026-19474 is a high-severity flaw (CVSS 7.5) affecting fastify-multipart. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

@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

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.5% (top 58%)
CISA exploited list	No
Weakness	CWE-459, CWE-770
Published	2026-08-15
Last modified	2026-09-02

Publisher (CNA): openjs · Vendor: fastify

Last updated 2026-09-02 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-08-15 14:17 UTCPublished CVE record published
2026-09-02 15:12 UTCUpdated Record last modified

fastify fastify-multipart UPGRADE

Affected: >= 3.0.0 and < 10.1.1

Fixed in: 10.1.1

Safe to downgrade to: a release before 3.0.0

1. Check installed version

apt-cache policy fastify-multipart || rpm -q fastify-multipart || fastify-multipart --version

2. UPGRADE to 10.1.1 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade fastify-multipart

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade fastify-multipart

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 3.0.0 (Debian / Ubuntu)

apt-cache madison fastify-multipart sudo apt install fastify-multipart=<VERSION_BEFORE_3.0.0> sudo apt-mark hold fastify-multipart

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list fastify-multipart sudo dnf downgrade fastify-multipart-<VERSION_BEFORE_3.0.0> sudo dnf versionlock add fastify-multipart

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-19474?

fastify-multipart: upgrade to 10.1.1. Exact commands for each OS are on this page.

Is CVE-2026-19474 being exploited?

CVE-2026-19474 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-19474 affect?

CVE-2026-19474 affects fastify-multipart. Severity is high (CVSS 7.5). @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 adva

How urgent is CVE-2026-19474?

Priority 42/100. High severity; Remotely exploitable, no login, no user action

Related CVEs

CVE-2026-18549 HIGH 7.5 UPGRADE @fastify/multipart is a multipart form-data parser for Fastify

References

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