CVE-2026-19484
Received
Received - Intake
Denial of Service in @fastify/busboy via Boundary Length
Vulnerability report for CVE-2026-19484, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-08-13
Last updated on: 2026-08-13
Assigner: openjs
Description
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.
CVSS Scores
EPSS Scores
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| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| fastify | busboy | From 3.1.0 (inc) to 3.2.1 (exc) |
| fastify | busboy | 3.2.1 |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-835 | The product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop. |
| CWE-1322 | The product uses a non-blocking model that relies on a single threaded process for features such as scalability, but it contains code that can block when it is invoked. |
