CVE-2026-19484
@fastify/busboy vulnerable to Denial of Service via oversized multipart boundary
Description
@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.
INFO
Published Date :
Aug. 13, 2026, 10:17 a.m.
Last Modified :
Sept. 3, 2026, 7:10 p.m.
Remotely Exploit :
No
Source :
ce714d77-add3-4f53-aff5-83d477b104bb
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | HIGH | ce714d77-add3-4f53-aff5-83d477b104bb | ||||
| CVSS 3.1 | HIGH | MITRE-CVE |
Solution
- Upgrade @fastify/busboy to version 3.2.1.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-19484.
| URL | Resource |
|---|---|
| https://cna.openjsf.org/security-advisories.html | Third Party Advisory |
| https://github.com/fastify/busboy/security/advisories/GHSA-xjh9-v7x6-24jw | Vendor Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-19484 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-19484
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-19484 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-19484 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
Sep. 03, 2026
Action Type Old Value New Value Added CPE Configuration OR *cpe:2.3:a:fastify:fastify/busyboy:*:*:*:*:*:node.js:*:* versions from (including) 3.1.0 up to (excluding) 3.2.1 Added Reference Type openjs: https://cna.openjsf.org/security-advisories.html Types: Third Party Advisory Added Reference Type openjs: https://github.com/fastify/busboy/security/advisories/GHSA-xjh9-v7x6-24jw Types: Vendor Advisory -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Aug. 13, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-19484', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'yes'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-08-13T14:26:38.443138Z'} -
New CVE Received by ce714d77-add3-4f53-aff5-83d477b104bb
Aug. 13, 2026
Action Type Old Value New Value Added Affected [{'vendor': '@fastify/busboy', 'product': '@fastify/busboy', 'versions': [{'status': 'affected', 'version': '3.1.0', 'lessThan': '3.2.1', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '3.2.1', 'versionType': 'semver'}], 'packageURL': 'pkg:npm/@fastify/busboy', 'defaultStatus': 'unaffected'}] Added Description @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. Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Added CWE CWE-835 Added CWE CWE-1322 Added Reference https://cna.openjsf.org/security-advisories.html Added Reference https://github.com/fastify/busboy/security/advisories/GHSA-xjh9-v7x6-24jw