CVE-2026-19484: @fastify/busboy is a multipart form-data parser

Q: How do I fix CVE-2026-19484?

fastify\/busyboy: upgrade to 3.2.1. Exact commands for each OS are on this page.

Q: Is CVE-2026-19484 being exploited?

CVE-2026-19484 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-19484 affect?

CVE-2026-19484 affects fastify\/busyboy. Severity is high (CVSS 7.5). @fastify/busboy is a multipart form-data parser. In versions 3.1.0 through 3.2.0, a remote unauthenticated attacker can stall the Node.js event loop by sending a multipart request whose boundary is crafted to a specific length. The vendored

Q: How urgent is CVE-2026-19484?

Priority 44/100. High severity; Remotely exploitable, no login, no user action

This month

HIGH 7.5REMOTEUPGRADE

CVE-2026-19484 is a high-severity flaw (CVSS 7.5) affecting fastify\/busyboy. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

@fastify/busboy is a multipart form-data parser. In versions 3.1.0 through 3.2.0, a remote unauthenticated attacker can stall the Node.js event loop by sending a multipart request whose boundary is crafted to a specific length. The vendored streaming search stores its skip table in a fixed 256 entry byte array, and a boundary of exactly 252 bytes makes the search needle 256 bytes, which truncates the default skip distance to zero and turns the se

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	0.6% (top 51%)
CISA exploited list	No
Weakness	CWE-835, CWE-1322
Published	2026-08-13
Last modified	2026-09-03

Publisher (CNA): openjs · Vendor: fastify

Last updated 2026-09-03 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-08-13 10:17 UTCPublished CVE record published
2026-09-03 19:10 UTCUpdated Record last modified

fastify fastify\/busyboy UPGRADE

Affected: >= 3.1.0 and < 3.2.1

Fixed in: 3.2.1

Safe to downgrade to: a release before 3.1.0

1. Check installed version

npm ls fastifybusyboy

2. UPGRADE to 3.2.1

npm install fastifybusyboy@">=3.2.1"

3. If no update is available yet, DOWNGRADE to a release before 3.1.0

npm view fastifybusyboy versions npm install fastifybusyboy@"<3.1.0"

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-2026-19484?

fastify\/busyboy: upgrade to 3.2.1. Exact commands for each OS are on this page.

Is CVE-2026-19484 being exploited?

CVE-2026-19484 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-2026-19484 affect?

CVE-2026-19484 affects fastify\/busyboy. Severity is high (CVSS 7.5). @fastify/busboy is a multipart form-data parser. In versions 3.1.0 through 3.2.0, a remote unauthenticated attacker can stall the Node.js event loop by sending a multipart request whose boundary is crafted to a specific length. The vendored

How urgent is CVE-2026-19484?

Priority 44/100. High severity; Remotely exploitable, no login, no user action

Software pages

Node.js vulnerabilities

Related CVEs

CVE-2026-74866 MEDIUM 5.8 UPGRADE @fastify/busboy is a multipart form-data parser for Node.js
CVE-2026-19481 HIGH 7.5 UPGRADE @fastify/busboy is a multipart form-data parser

References

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