Vulnerabilities in pkg:npm/@fastify/busboy

PACKAGE
Advisory Identifier: GHSA-gxm5-99cw-xjw9
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Advisory Summary

CVE-2026-74866 is a MODERATE (CVSS 5.8) @fastify/busboy vulnerable to crlf injection vulnerability (CWE-93: Improper Neutralization of CRLF Sequences ('CRLF Injection')) affecting @fastify/busboy libraries in the npm ecosystem. The issue involves @fastify/busboy vulnerable to crlf injection via multipart content-disposition filename and name. Remediation is available by upgrading affected packages to version 3.2.2.

3 Known Advisory Record(s)
Package Vulnerability Intelligence

pkg:npm/@fastify/busboy

3 Known Advisory Record(s)

Vulnerability advisories affecting package pkg:npm/@fastify/busboy. Select an advisory below to view technical details or fixes.

Advisory ID CVE / NVD Severity Summary
GHSA-gxm5-99cw-xjw9 CVE-2026-74866 MODERATE @fastify/busboy vulnerable to CRLF injection via multipart Content-Disposition filename and name
GHSA-x8mw-p69m-v3mx CVE-2026-19481 HIGH @fastify/busboy vulnerable to Denial of Service via prototype-named multipart part header
GHSA-xjh9-v7x6-24jw CVE-2026-19484 HIGH @fastify/busboy vulnerable to Denial of Service via oversized multipart boundary

CVE-2026-74866 at a Glance

CVE Identifier CVE-2026-74866
GHSA Identifier GHSA-gxm5-99cw-xjw9
Severity MODERATE
CVSS v3.1 Base Score 5.8
CWE Classification CWE-93: Improper Neutralization of CRLF Sequences ('CRLF Injection')
Affected Product @fastify/busboy
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 5.8

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Changed (S:C)
Confidentiality None (C:N)
Integrity Low (I:L)
Availability None (A:N)

How to Fix CVE-2026-74866

To remediate this vulnerability, upgrade all affected @fastify/busboy dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

@fastify/busboy fixed: 3.2.2 
npm install @fastify/busboy@3.2.2
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

npm ls @fastify/busboy

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-74866, inspect your project dependencies using npm:

npm ls @fastify/busboy

Analyze the terminal output to locate any version of @fastify/busboy in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 3.2.2), your application is affected.

Note: The npm ls @fastify/busboy command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-93: Improper Neutralization of CRLF Sequences ('CRLF Injection'), where the product uses crlf (carriage return line feeds) as a special element, e.g. to separate lines or records, but it does not neutralize or incorrectly neutralizes crlf sequences from inputs. In @fastify/busboy, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Impact `@fastify/busboy` 3.2.1 and earlier retains a bare carriage return or line feed inside the parsed `Content-Disposition` parameters returned to the application. The multipart header parser ends a header line only on the two-byte `\r\n` sequence, so a lone CR or LF embedded in a part header is carried verbatim into the `filename` and field `name` delivered by the `file` and `field` events. An application that forwards the supplied filename or name into a CR/LF-sensitive sink cannot anticipate the embedded control character. An attacker who uploads a file whose `filename` or field `name` contains a bare CR or LF can pollute filenames on disk when the upload is saved under its original name, inject forged lines into logs, or inject headers on a downstream hop that does not re-validate CR/LF, such as object-storage metadata or a proxied backend. Applications using `@fastify/busboy` directly, or through `@fastify/multipart` and its consumers, are affected. ### Patches Upgrade to `@fastify/busboy` 3.2.2 or later. ### Workarounds Validate or strip carriage return and line feed characters from the `filename` and field `name` before using them in any filesystem, logging, or outbound-header context.

CVE-2026-74866 Affected @fastify/busboy Versions

1 component(s)
Fixed Versions:
3.2.2
Product / Package Ecosystem Affected Versions Fixed Version
@fastify/busboy
npm/@fastify/busboy
npm
< 3.2.2
3.2.2

References

GitHub Advisory / Wiki ADVISORY
https://github.com/fastify/busboy/security/advisories/GHSA-gxm5-99cw-xjw9
NVD — CVE-2026-74866 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-74866
Security Fix Commit FIX COMMIT
https://github.com/fastify/busboy/commit/cc7da17c5c88d79c314a9e149a79e5a00a6c23be
@fastify/busboy Security Information SECURITY
https://cna.openjsf.org/security-advisories.html
@fastify/busboy Source Repository REPOSITORY
https://github.com/fastify/busboy
@fastify/busboy Release RELEASE
https://github.com/fastify/busboy/releases/tag/v3.2.2

Frequently Asked Questions

What is CVE-2026-74866?
CVE-2026-74866 is a security vulnerability in @fastify/busboy involving @fastify/busboy vulnerable to CRLF injection via multipart Content-Disposition filename and name under CWE-93: Improper Neutralization of CRLF Sequences ('CRLF Injection').
Which @fastify/busboy versions are affected?
Affected versions include releases prior to 3.2.2 across affected packages: @fastify/busboy.
What version fixes CVE-2026-74866?
Upgrading to 3.2.2 (or the latest patched release for your respective branch) resolves the vulnerability.
Is @fastify/busboy affected?
Yes, @fastify/busboy is affected in releases prior to 3.2.2. Upgrade your dependency to 3.2.2 or later.
What is the CVSS score of CVE-2026-74866?
CVE-2026-74866 has a CVSS v3.1 base score of 5.8 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N.
What CWE is associated with CVE-2026-74866?
CVE-2026-74866 is classified under CWE-93: Improper Neutralization of CRLF Sequences ('CRLF Injection') (The product uses CRLF (carriage return line feeds) as a special element, e.g. to separate lines or records, but it does not neutralize or incorrectly neutralizes CRLF sequences from inputs.).
How can I check npm dependencies for CVE-2026-74866?
Run the dependency tree command: 'npm ls @fastify/busboy'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-gxm5-99cw-xjw9",
  "modified" : "2026-10-05T22:33:44Z",
  "published" : "2026-10-05T22:33:44Z",
  "aliases" : [ "CVE-2026-74866" ],
  "summary" : "@fastify/busboy vulnerable to CRLF injection via multipart Content-Disposition filename and name",
  "details" : "### Impact\n\n`@fastify/busboy` 3.2.1 and earlier retains a bare carriage return or line feed inside the parsed `Content-Disposition` parameters returned to the application. The multipart header parser ends a header line only on the two-byte `\\r\\n` sequence, so a lone CR or LF embedded in a part header is carried verbatim into the `filename` and field `name` delivered by the `file` and `field` events. An application that forwards the supplied filename or name into a CR/LF-sensitive sink cannot anticipate the embedded control character.\n\nAn attacker who uploads a file whose `filename` or field `name` contains a bare CR or LF can pollute filenames on disk when the upload is saved under its original name, inject forged lines into logs, or inject headers on a downstream hop that does not re-validate CR/LF, such as object-storage metadata or a proxied backend. Applications using `@fastify/busboy` directly, or through `@fastify/multipart` and its consumers, are affected.\n\n### Patches\n\nUpgrade to `@fastify/busboy` 3.2.2 or later.\n\n### Workarounds\n\nValidate or strip carriage return and line feed characters from the `filename` and field `name` before using them in any filesystem, logging, or outbound-header context.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N"
  } ],
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      }, {
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      } ]
    } ]
  } ],
  "references" : [ {
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  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-74866"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/fastify/busboy/commit/cc7da17c5c88d79c314a9e149a79e5a00a6c23be"
  }, {
    "type" : "WEB",
    "url" : "https://cna.openjsf.org/security-advisories.html"
  }, {
    "type" : "PACKAGE",
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  }, {
    "type" : "WEB",
    "url" : "https://github.com/fastify/busboy/releases/tag/v3.2.2"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-93" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-10-05T22:33:44Z",
    "nvd_published_at" : "2026-08-21T09:16:40Z"
  }
}