Vulnerability-Lookup

GHSA-XJH9-V7X6-24JW

Vulnerability from github – Published: 2026-10-02 23:16 – Updated: 2026-10-02 23:16

Summary

@fastify/busboy vulnerable to Denial of Service via oversized multipart boundary

Details

Impact

Versions of @fastify/busboy from 3.1.0 and prior to 3.2.1 are vulnerable to a Denial of Service. The vendored streaming multipart search stores its default skip distance in a Uint8Array(256). A multipart boundary of exactly 252 bytes makes the search needle 256 bytes, and the table entry wraps to zero, so a crafted request keeps the search in a CPU-bound loop and stalls the Node.js event loop. An unauthenticated client can trigger this with a single small request. Applications that use @fastify/busboy to parse multipart/form-data, directly or through @fastify/multipart, are affected.

Patches

Fixed in version 3.2.1.

Workarounds

Validate the multipart boundary before parsing and reject any boundary longer than the RFC 2046 limit of 70 characters (for example at a reverse proxy or in an onRequest hook). Upgrading to 3.2.1 removes the issue.

Severity

7.5 (High)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "@fastify/busboy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "3.1.0"
            },
            {
              "fixed": "3.2.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-19484"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1322",
      "CWE-835"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-10-02T23:16:17Z",
    "nvd_published_at": "2026-08-13T10:17:11Z",
    "severity": "HIGH"
  },
  "details": "### Impact\n\nVersions of `@fastify/busboy` from 3.1.0 and prior to 3.2.1 are vulnerable to a Denial of Service. The vendored streaming multipart search stores its default skip distance in a `Uint8Array(256)`. A multipart boundary of exactly 252 bytes makes the search needle 256 bytes, and the table entry wraps to zero, so a crafted request keeps the search in a CPU-bound loop and stalls the Node.js event loop. An unauthenticated client can trigger this with a single small request. Applications that use `@fastify/busboy` to parse multipart/form-data, directly or through `@fastify/multipart`, are affected.\n\n### Patches\n\nFixed in version 3.2.1.\n\n### Workarounds\n\nValidate the multipart boundary before parsing and reject any boundary longer than the RFC 2046 limit of 70 characters (for example at a reverse proxy or in an onRequest hook). Upgrading to 3.2.1 removes the issue.",
  "id": "GHSA-xjh9-v7x6-24jw",
  "modified": "2026-10-02T23:16:17Z",
  "published": "2026-10-02T23:16:17Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/fastify/busboy/security/advisories/GHSA-xjh9-v7x6-24jw"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-19484"
    },
    {
      "type": "WEB",
      "url": "https://github.com/fastify/busboy/commit/632a237e7fb6b3b7a30e0de8fab2ee72ca5bf722"
    },
    {
      "type": "WEB",
      "url": "https://cna.openjsf.org/security-advisories.html"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/fastify/busboy"
    },
    {
      "type": "WEB",
      "url": "https://github.com/fastify/busboy/releases/tag/v3.2.1"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "@fastify/busboy vulnerable to Denial of Service via oversized multipart boundary"
}

CVE-2026-19484 (GCVE-0-2026-19484)

Vulnerability from cvelistv5 – Published: 2026-08-13 08:50 – Updated: 2026-08-13 14:27

Title

@fastify/busboy vulnerable to Denial of Service via oversized multipart boundary

Summary

@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 search into a CPU bound loop on a small body. A single small request can keep one core busy and deny service to other requests handled by the same process. The issue is fixed in @fastify/busboy 3.2.1, which widens the skip table so the skip distance is preserved. Users should upgrade to 3.2.1.

Severity

7.5 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

SSVC

Exploitation: none Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-08-13 14:26 UTC

CWE

CWE-835 - Loop with Unreachable Exit Condition ('Infinite Loop')
CWE-1322 - Use of Blocking Code in Single-threaded, Non-blocking Context

Assigner

openjs redhat root Scorecard

References

2 references

URL	Tags
https://github.com/fastify/busboy/security/adviso…
https://cna.openjsf.org/security-advisories.html

Impacted products

1 product

Vendor	Product	Version
@fastify/busboy	@fastify/busboy	Affected: 3.1.0 , < 3.2.1 (semver) Unaffected: 3.2.1 (semver)

Credits

LorenzoRD2003 mcollina UlisesGascon

Show details on NVD website

JSON

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Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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