[ CVE-2026-19484 · Published 13 Aug 2026 ]
@fastify/busboy vulnerable to Denial of Service via oversized multipart boundary
[ Description ]Official 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.
[ Fixes ]Fixes and patches
- @fastify/busboy 3.2.1Fixed version · GitHub Advisories · npm package @fastify/busboy: upgrade to 3.2.1 or later (affected >= 3.1.0, < 3.2.1)
[ Packages ]Affected open-source packages
- @fastify/busboy npmAffected >= 3.1.0, < 3.2.1 · fixed in 3.2.1 · GHSA-xjh9-v7x6-24jw