CVE-2026-74866: @fastify/busboy is a multipart form-data parser for Node.js

Routine

MEDIUM 5.8REMOTEUPGRADE

CVE-2026-74866 is a medium-severity flaw (CVSS 5.8) 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 for Node.js. Its multipart part-header parser splits header lines only on the two-byte carriage-return line-feed sequence, so a lone carriage return or line feed embedded in a part header is not treated as a line break and is carried verbatim into the parsed Content-Disposition filename and field name handed to the application. An attacker who uploads a file whose filename or field name contains a b

Why this priority

Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	5.8 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.3% (top 75%)
CISA exploited list	No
Weakness	CWE-93
Published	2026-08-21
Last modified	2026-10-16

Publisher (CNA): openjs · Vendor: fastify

Last updated 2026-10-16 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-08-21 09:16 UTCPublished CVE record published
2026-10-16 15:10 UTCUpdated Record last modified

fastify fastify\/busyboy UPGRADE

Affected: < 3.2.2

Fixed in: 3.2.2

Safe to downgrade to: no unaffected older release

1. Check installed version

npm ls fastifybusyboy

2. UPGRADE to 3.2.2

npm install fastifybusyboy@">=3.2.2"

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-2026-74866?

fastify\/busyboy: upgrade to 3.2.2. Exact commands for each OS are on this page.

Is CVE-2026-74866 being exploited?

CVE-2026-74866 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-2026-74866 affect?

CVE-2026-74866 affects fastify\/busyboy. Severity is medium (CVSS 5.8). @fastify/busboy is a multipart form-data parser for Node.js. Its multipart part-header parser splits header lines only on the two-byte carriage-return line-feed sequence, so a lone carriage return or line feed embedded in a part header is n

How urgent is CVE-2026-74866?

Priority 32/100. Remotely exploitable, no login, no user action

Software pages

Node.js vulnerabilities

Related CVEs

CVE-2026-19481 HIGH 7.5 UPGRADE @fastify/busboy is a multipart form-data parser
CVE-2026-19484 HIGH 7.5 UPGRADE @fastify/busboy is a multipart form-data parser

References

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