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OpenAdvisories
High · 7.5 CVE-2026-19484 EUVD-2026-57759GHSA-xjh9-v7x6-24jw

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

Published Aug 13, 2026 · Updated Aug 13, 2026 · Assigned by openjs

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.

Affected products

VendorProductAffectedFixed
@fastify/busboy @fastify/busboy 3.1.0 – < 3.2.1 3.2.1

Fixed in Linux distributions

Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.

Wolfi

ReleasePackageFixed inAdvisory
Wolfi rolling langfuse-3-worker 3.225.11-r5 —

Affected packages

EcosystemPackageAffectedFixedRecord
npm @fastify/busboy >= 3.1.0, < 3.2.1 3.2.1 GHSA-xjh9-v7x6-24jw

References